Methods of epicardial ablation for creating a lesion around the pulmonary veins

ABSTRACT

The invention provides surgical systems and methods for ablating heart tissue within the interior and/or exterior of the heart. A plurality of probes is provided with each probe configured for introduction into the chest for engaging the heart. Each probe includes an elongated shaft having an elongated ablating surface of a predetermined shape. The elongated shaft and the elongated ablating surface of each probe are configured to ablate a portion of the heart. A sealing device affixed to the heart tissue forms a hemostatic seal between the probe and the penetration in the heart to inhibit blood loss therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of commonly-assigned,application Ser. No. 08/735,036 filed Oct. 22, 1996, now abandoned;which is a continuation-in-part of application Ser. No. 08/425,179,filed Apr. 20, 1995, now U.S. Pat. No. 5,797,960; which is acontinuation-in-part of application Ser. No. 08/163,241, filed Dec. 6,1993, now U.S. Pat. No. 5,571,215, issued Nov. 5, 1996; which is acontinuation-in-part of application Ser. No. 08/023,778, filed Feb. 22,1993, now U.S. Pat. No. 5,452,733, issued Sep. 26, 1995. The completedisclosures of these applications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

It is well documented that atrial fibrillation, either alone or as aconsequence of other cardiac disease, continues to persist as the mostcommon cardiac arrhythmia. According to recent estimates, more than onemillion people in the U.S. suffer from this common arrhythmia, roughly0.15% to 1.0% of the population. Moreover, the prevalence of thiscardiac disease increases with age, affecting nearly 8% to 17% of thoseover 60 years of age.

Although atrial fibrillation may occur alone, this arrhythmia oftenassociates with numerous cardiovascular conditions, including congestiveheart failure, hypertensive cardiovascular disease, myocardialinfarcation, rheumatic heart disease and stroke. Regardless, threeseparate detrimental sequelae result: (1) a change in the ventricularresponse, including the onset of an irregular ventricular rhythm and anincrease in ventricular rate; (2) detrimental hemodynamic consequencesresulting from loss of atroventricular synchrony, decreased ventricularfilling time, and possible atrioventricular valve regurgitation; and (3)an increased likelihood of sustaining a thromboembolic event because ofloss of effective contraction and atrial stasis of blood in the leftatrium.

Atrial arrythmia may be treated using several methods. Pharmacologicaltreatment of atrial fibrillation, for example, is initially thepreferred approach, first to maintain normal sinus rhythm, or secondlyto decrease the ventricular response rate. While these medications mayreduce the risk of thrombus collecting in the atrial appendages if theatrial fibrillation can be converted to sinus rhythm, this form oftreatment is not always effective. Patients with continued atrialfibrillation and only ventricular rate control continue to suffer fromirregular heartbeats and from the effects of impaired hemodynamics dueto the lack of normal sequential atrioventricular contractions, as wellas continue to face a significant risk of thromboembolism.

Other forms of treatment include chemical cardioversion to normal sinusrhythm, electrical cardioversion, and RF catheter ablation of selectedareas determined by mapping. In the more recent past, other surgicalprocedures have been developed for atrial fibrillation, including leftatrial isolation, transvenous catheter or cryosurgical ablation of Hisbundle, and the Corridor procedure, which have effectively eliminatedirregular ventricular rhythm. However, these procedures have for themost part failed to restore normal cardiac hemodynamics, or alleviatethe patient's vulnerability to thromboembolism because the atria areallowed to continue to fibrillate. Accordingly, a more effectivesurgical treatment was required to cure medically refractory atrialfibrillation of the heart.

On the basis of electrophysiologic mapping of the atria andidentification of macroreentrant circuits, a surgical approach wasdeveloped which effectively creates an electrical maze in the atrium(i.e., the MAZE procedure) and precludes the ability of the atria tofibrillate. Briefly, in the procedure commonly referred to as the MAZEIII procedure, strategic atrial incisions are performed to preventatrial reentry and allow sinus impulses to activate the entire atrialmyocardium, thereby preserving atrial transport functionpostoperatively. Since atrial fibrillation is characterized by thepresence of multiple macroreentrant circuits that are fleeting in natureand can occur anywhere in the atria, it is prudent to interrupt all ofthe potential pathways for atrial macroreentrant circuits. Thesecircuits, incidentally, have been identified by intraoperative mappingboth experimentally and clinically in patients.

Generally, this procedure includes the excision of both atrialappendages, and the electrical isolation of the pulmonary veins.Further, strategically placed atrial incisions not only interrupt theconduction routes of the most common reentrant circuits, but they alsodirect the sinus impulse from the sinoatrial node to theatrioventricular node along a specified route. In essence, the entireatrial myocardium, with the exception of the atrial appendages and thepulmonary veins, is electrically activated by providing for multipleblind alleys off the main conduction route between the sinoatrial nodeto the atrioventricular node. Atrial transport function is thuspreserved postoperatively, as generally set forth in the series ofarticles: Cox, Schuessler, Boineau, Canavan, Cain, Lindsay, Stone,Smith, Corr, Chang, and D'Agostino, Jr., The Surgical Treatment ofAtrial Fibrillation (pts. 1-4), 101 THORAC CARDIOVASC SURG., 402-426,569-592 (1991).

While this MAZE III procedure has proven effective in ablating medicallyrefractory atrial fibrillation and associated detrimental sequelae, thisoperational procedure is traumatic to the patient since substantialincisions are introduced into the interior chambers of the heart.Moreover, using current techniques, many of these procedures require agross thoracotomy, usually in the form of a median sternotomy, to gainaccess into the patient's thoracic cavity. A saw or other cuttinginstrument is used to cut the sternum longitudinally, allowing twoopposing halves of the anterior or ventral portion of the rib cage to bespread apart. A large opening into the thoracic cavity is thus created,through which the surgical team may directly visualize and operate uponthe heart for the MAZE III procedure. Such a large opening furtherenables manipulation of surgical instruments and/or removal of excisedheart tissue since the surgeon can position his or her hands within thethoracic cavity in close proximity to the exterior of the heart. Thepatient is then placed on cardiopulmonary bypass to maintain peripheralcirculation of oxygenated blood.

Not only is the MAZE III procedure itself traumatic to the patient, butthe postoperative pain and extensive recovery time due to theconventional thoracotomy substantially increase trauma and furtherextend hospital stays. Moreover, such invasive, open-chest proceduressignificantly increase the risk of complications and the pain associatedwith sternal incisions. While heart surgery produces beneficial resultsfor many patients, numerous others who might benefit from such surgeryare unable or unwilling to undergo the trauma and risks of currenttechniques.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide asurgical procedure and system for closed-chest, closed heart ablation ofheart tissue.

It is another object of the present invention to provide a surgicalprocedure and system for ablating medically refractory atrialfibrillation.

Yet another object of the present invention is to provide a surgicalprocedure and surgical devices which are capable of strategicallyablating heart tissue from the interior chambers or external cardiacsurfaces thereof without substantially disturbing the structuralintegrity of the atria.

Still another object of the present invention is to enable surgeons toablate medically refractory atrial fibrillation while the heart is stillbeating.

In accordance with the foregoing objects of the invention, the presentinvention provides surgical systems and methods for ablating hearttissue within the interior and/or exterior of the heart. This procedureis particularly suitable for surgeries such as the MAZE III proceduredeveloped to treat medically refractory atrial fibrillation since theneed for substantial, elongated, transmural incisions of the heart wallsare eliminated. Moreover, this technique is preferably performed withouthaving to open the chest cavity via a median sternotomy or majorthoracotomy. The system is configured for being introduced through asmall intercostal, percutaneous penetration into a body cavity andengaging the heart wall through purse-string incisions. As a result, theprocedure of the present invention reduces potential postoperativecomplications, recovery time and hospital stays.

A system for transmurally ablating heart tissue is provided including anablating probe having an elongated shaft positionable through the chestwall and into a transmural penetration extending through a muscular wallof the heart and into a chamber thereof. The shaft includes an elongatedablating surface for ablating heart tissue. The system of the presentinvention further includes a sealing device fixable to the heart tissuearound the transmural penetration for forming a hemostatic seal aroundthe probe to inhibit blood loss therethrough.

A preferred method and device for ablating the heart tissue is with acryosurgical ablation device. Although cryosurgical ablation is apreferred method, a number of other ablation methods could be usedinstead of cryoablation. Among these tissue ablation means are RadioFrequency (RF), ultrasound, microwave, laser, heat, localized deliveryof chemical or biological agents and light-activated agents to name afew.

More specifically, the system of the present invention enables theformation of a series of strategically positioned and shaped elongated,transmural lesions which cooperate with one another to reconstruct amain electrical conduction route between the sinoatrial node to theatrioventricular node. Atrial transport function is thus preservedpostoperatively for the treatment of atrial fibrillation.

The system includes a plurality of surgical probes each having anelongated shaft. Each shaft includes an elongated ablating surface of apredetermined shape for contact with at least one specific surface ofthe heart and specifically the interior walls of atria chamber. Suchcontact with the ablating surface for a sufficient period of time causestransmural ablation of the wall. Collectively, a series of strategicallypositioned and shaped elongated, transmural lesions are formed whichcooperate with one another to treat atrial fibrillation. Each transmuralpenetration includes a purse-string suture formed in the heart tissuearound the respective transmural penetration in a manner forming ahemostatic seal between the respective probe and the respectivetransmural penetration to inhibit blood loss therethrough.

When using a cryosurgical probe, the probe includes a shaft having adelivery passageway for delivery of pressurized cryogen therethrough andan exhaust passageway for exhaust of expended cryogen. The pressurizedcryogen is expanded in a boiler chamber thereby cooling the elongatedablating surface for cryogenic cooling of the elongated ablatingsurface. The elongated shaft is configured to pass through the chestwall and through a penetration in the patient's heart for ablativecontact with a selected portion of the heart.

In another aspect of the present invention, a surgical method forablating heart tissue from the interior and/or exterior walls of theheart is provided including the steps of forming a penetration through amuscular wall of the heart into an interior chamber thereof andpositioning an elongated ablating device having an elongated ablatingsurface through the penetration. The method further includes the stepsof forming a hemostatic seal between the device and the heart wallpenetration to inhibit blood loss through the penetration and contactingthe elongated ablating surface of the ablating device with a firstselected portion of an interior and/or exterior surface of the muscularwall for ablation thereof.

More preferably, a method for ablating medically refractory atrialfibrillation of the heart is provided comprising the steps of forming apenetration through the heart and into a chamber thereof positioning anelongated ablating devices having an elongated ablating surface throughthe penetration and forming a hemostatic seal between the ablatingdevice and the penetration to inhibit blood loss therethrough. Thepresent invention method further includes the steps of strategicallycontacting the elongated ablating surface of the ablating device with aportion of the muscular wall for transmural ablation thereof to form atleast one elongated transmural lesion and repeating these steps for eachremaining lesion. Each transmural lesion is formed through contact withthe ablating surface of one of the plurality of ablating device and thestrategically positioned elongated transmural lesions cooperate to guidethe electrical pulse pathway along a predetermined path for the surgicaltreatment of atrial fibrillation.

The entire procedure is preferably performed through a series of onlyfive purse-strings sutures strategically located in the right and leftatria, and pulmonary vein portions. Generally, multiple lesions can beformed through a single purse-string either through the use of assorteduniquely shaped ablating devices or through the manipulation of a singleablating device.

It should be understood that while the invention is described in thecontext of thoracoscopic surgery on the heart, the systems and methodsdisclosed herein are equally useful to ablate other types of tissuestructures and in other types of surgery such as laparoscopy andpelviscopy.

The procedure and system of the present invention have other objects ofadvantages which will be readily apparent from the following descriptionof the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an upper left, posterior perspective view of a human heartincorporating the system and procedure for treatment of medicallyrefractory atrial fibrillation constructed in accordance with theprinciples of the present invention.

FIG. 2 is a right, antero-lateral perspective view of the human heartincorporating the present invention system and procedure thereof.

FIGS. 3A and 3B are schematic diagrams of the atria portion of the heartillustrating the pattern of transmural cryolesions to create apredetermined conduction path in the atrium using the system andprocedure of the present invention.

FIG. 4 is a top plan view of a set of cryoprobe devices constructed inaccordance with the present invention, and utilized in the system andprocedure of the present invention.

FIG. 5 is a top perspective view of a patient showing use of the systemand procedure on the patient.

FIG. 6 is an enlarged, fragmentary, top plan view, in cross-section, ofone of the cryoprobes in the set of cryoprobes of FIG. 4, illustratingthe expansion chamber thereof.

FIGS. 6A-6D illustrate use of a slidable insulative tube for insulatingportions of the probe.

FIG. 7 is a front elevation view, in-cross-section, of the ablating endof a cryoprobe, taken substantially along the plane of the line 7--7 inFIG. 6.

FIG. 8 is a front elevation view, in cross-section, of an alternativeembodiment of the ablating end of FIG. 7.

FIG. 9 is a transverse cross-sectional view of the system and patient,taken through the patient's thorax generally along the plane of the line9--9 in FIG. 11A, showing the relative positioning of the right and leftintercostal percutaneous penetrations.

FIG. 10 is a front schematic view of a patient's cardiovascular systemillustrating the positioning of a cardiopulmonary bypass system forarresting the heart and establishing cardiopulmonary bypass inaccordance with the principles of the present invention.

FIGS. 11A-11D is a series of top plan views of the patient undergoing apericardiotomy as well as the installation of a purse-string suture anda stay suture to assist in suspending the pericardium.

FIGS. 12A-12C is a series of enlarged, fragmentary side elevation viewslooking into the patient's thoracic cavity at the right atrium through asoft tissue retractor (not shown) in the system of FIG. 5, andillustrating the introduction of cryoprobes constructed in accordancewith the present invention through purse-strings for the formation of aposterior longitudinal right atrial cryolesion and a tricuspid valveannulus cryolesion.

FIG. 13 is an enlarged, fragmentary, transverse cross-sectional view,partially broken away, of the system and patient's heart of FIG. 5, andillustrating the introduction of a tricuspid valve cryoprobe through apurse-string suture in the right atrial freewall to form the elongated,transmural, tricuspid valve annulus cryolesion.

FIG. 14 is a side elevation view peering at the right atrial appendagethrough the soft tissue retractor passageway (not shown) in the systemof FIG. 5, showing the formation of a perpendicular right atrialcryolesion.

FIG. 15 is a fragmentary, transverse cross-sectional view of the systemand patient's heart, illustrating the formation of a right atrialanteromedial counter cryolesion.

FIG. 16 is an upper left, posterior perspective view the human heart ofFIG. 1, illustrating the location of the purse-string sutures in theright and left atrial walls, to access opposite sides of the atrialseptum wall for the introduction of an atrial septum clamping cryoprobe.

FIG. 17 is a fragmentary, transverse cross-sectional view, partiallybroken away, of the system and patient's heart, showing the atrialseptum clamping cryoprobe engaged with the atrial septum wall for theformation of an anterior limbus of the fossa ovalis cryolesion.

FIGS. 18A and 18B is a sequence of enlarged, fragmentary, transversecross-sectional views, partially broken away, of the system andpatient's heart, illustrating the technique employed to enable insertionof the distal ends of the atrial septum clamping cryoprobe through theadjacent purse-string sutures.

FIGS. 19A-19D is a series of fragmentary, transverse cross-sectionalviews, partially broken away, of the system and patient's heart, showingthe formation of an endocardial pulmonary vein isolation cryolesionusing a four-step process.

FIGS. 20A and 20B is a sequence of fragmentary, transversecross-sectional views, partially broken away, of the system andpatient's heart, showing the formation of the pulmonary vein isolationcryolesion through an alternative two-step process.

FIG. 21 is an upper left, posterior perspective view of the human heartillustrating the formation of an additional epicardial pulmonary veinisolation cryolesion.

FIG. 22 is a fragmentary, transverse cross-sectional view of the systemand patient's heart, showing the formation of a left atrial anteromedialcryolesion.

FIG. 23 is a fragmentary, transverse cross-sectional view of the systemand patient's heart, illustrating the formation of a posterior verticalleft atrial cryolesion.

FIG. 24 is a top plan view of the right angle cryoprobe of FIGS. 12A and12B.

FIG. 25 is a top plan view of the tricuspid valve annulus cryoprobe ofFIG. 13.

FIG. 26 is a top plan view of an alternative embodiment of the tricuspidvalve annulus cryoprobe of FIG. 25.

FIG. 27 is a top plan view of the right atrium counter lesion cryoprobeof FIG. 15.

FIG. 28 is a top plan view of the atrial septum clamping cryoprobe ofFIGS. 17 and 18.

FIG. 29 is an enlarged front elevation view, in cross-section, of acoupling device of the septum clamping cryoprobe, taken substantiallyalong the plane of the line 29--29 in FIG. 28.

FIG. 30 is an enlarged rear elevation view, in cross-section, of analigning device of the septum clamping cryoprobe, taken substantiallyalong the plane of the line 30--30 in FIG. 28.

FIG. 31 is an enlarged, fragmentary, top plan view of an alternativeembodiment to the atrial septum clamping cryoprobe of FIG. 28.

FIG. 32 is a top plan view of an all-purpose cryoprobe of FIGS. 19A and19B.

FIG. 33 is a top plan view of the pulmonary vein loop cryoprobe of FIGS.20 and 21.

FIG. 34 is a top plan view of the left atrial anteromedical cryoprobe ofFIG. 22.

FIG. 35 is a top plan view of an alternative embodiment of theall-purpose cryoprobe of FIG. 23.

FIG. 36 is an enlarged, fragmentary, top plan view of an alternativeembodiment to the cryoprobes formed for contact of the ablation surfacewith the epicardial surface of the heart.

FIG. 37 is an exploded view of a cryogen delivery tube.

FIG. 38 is a partial cross-sectional view of the probe having thedelivery tube of FIG. 37.

FIG. 39 is an exploded view of the outer tube of the probe of FIG. 38.

FIG. 40 is an end view of the ablating surface of the probe of FIG. 39.

FIG. 41 shows a probe having a delivery tube with adjustable holeswherein an outer tube is slidably movable relative to an inner tube.

FIG. 42 shows the probe of FIG. 41 with the outer tube moved distallyrelative to the inner tube.

FIG. 43 shows a probe having vacuum ports for adhering the probe to thetissue to be ablated.

FIG. 44 is a cross-sectional view of the probe of FIG. 43 along lineI--I.

FIG. 45 shows a probe having a malleable shaft.

FIG. 46 shows the tip of the probe of FIG. 45.

FIG. 47 is a cross-sectional view of the probe of FIG. 45 along lineII--II.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Attention is now directed to FIGS. 1-3 where a human heart H isillustrated incorporating a series of strategically positionedtransmural lesions throughout the right atrium RA and the left atrium LAformed with the heart treatment procedure and system of the presentinvention. FIG. 1 represents the desired pattern of lesions created onthe right atrium RA, including the posterior longitudinal right atriallesion 50, the tricuspid valve annulus lesion valve annulus lesion 51,the pulmonary vein isolation lesion vein isolation lesion 52 and theperpendicular lesion 53; while FIG. 2 represents a right, anteriorperspective view of the heart H illustrating right atrium RA including aright atrial anteromedial counter lesion 55. The cumulative pattern oflesions reconstruct a main electrical conduction route between thesinoatrial node to the atrioventricular node to postoperatively preserveatrial transport function. Unlike prior surgical treatments, the systemand procedure of the present invention, generally designated 56 in FIGS.4 and 5, employ a closed-heart technique which eliminates the need forgross multiple elongated incisions of the atria to ablate heart tissuein the manner sufficient to preclude electrical conduction of reentrantpathways in the atria.

In accordance with the heart treatment procedure and system of thepresent invention, a set of uniquely-shaped, elongated tip ablationprobes 57 (FIG. 4, to be discussed in detail below) are employed whichare formed and dimensioned for insertion through at least one of aplurality of heart wall penetrations, preferably sealed by means ofpurse-string sutures 58, 60, 61, 62 and 63, strategically positionedabout the atria of the heart H. Once the distal end of the probe isinserted through the desired purse-string suture, an elongated ablatingsurface 65 thereof is maneuvered into contact with the selectedendocardial surface of an interior wall of the atria to create anelongated, transmural lesion. As shown in FIGS. 3A and 3B, theseindividual lesions collectively form a pattern of transmurally ablatedheart tissue to surgically treat medically refractory atrialfibrillation.

Briefly, FIG. 4 represents a collection or set of probes 57 constructedin accordance with the present invention which are employed to precludeelectrical conduction of reentrant pathways in the atria usingclosed-heart surgical techniques. Collectively, as will be apparent, theprobes enable the surgical formation of a series of lesions which areillustrated in FIGS. 3A and 3B. Each probe (FIGS. 24-28 and 32-35)includes an elongated shaft 66 formed to extend through an access portor passageway 67 in a retractor 68 (FIG. 5) which is mounted in apercutaneous intercostal penetration. The terms "percutaneousintercostal penetration" and "intercostal penetration" as used hereinrefer to a penetration, in the form or a cut, incision, hole, retractor,cannula, trocar sleeve, or the like, through the chest wall between twoadjacent ribs wherein the patient's rib cage and sternum remaingenerally intact. These terms are intended to distinguish a grossthoracotomy, such as a median sternotomy, wherein the sternum and/or oneor more ribs are cut or removed from the rib cage. It should beunderstood that one or more ribs may be retracted to widen theintercostal space between adjacent ribs without departing from the scopeof the invention.

Proximate the distal end of each probe is an elongated ablating end 70having an ablating surface 65 formed to transmurally ablate hearttissue. Access to the selected portions of the atria of the heart H areprovided by the specially shaped shafts 66 and ablating ends 70 whichare configured to position the elongated ablating surface 65 through thechest wall of patient P and through a strategically positionedpenetration in the muscular wall of the patient's heart H for ablativecontact with a selected portion of an interior surface of the muscularwall. Subsequent contact of the ablating surface 65 with specificselected wall portions of the atria enable selected, localizedtransmural ablation thereof.

In a preferred embodiment the probes 57 form the lesions by freezing theheart tissue. Although freezing is a preferred method of ablatingtissue, the probe 57 may use any other method such as RF ablation,ultrasound, microwave, laser, localized delivery of chemical orbiological agents, light-activated agents, laser ablation or resistanceheating ablation. Regarding the localized delivery of chemical orbiological agents, the device may include an injection device capable ofinjecting the chemical or biological agent onto or into the desiredtissue for localized ablation thereof. The source of the chemical orbiological agent may be stored in a reservoir contained in the probe orbe stored in an external reservoir coupled to the injecting end of theprobe.

When the probe freezes tissue during ablation, an opposite end of theprobe has a fitting 71 formed for releasable coupling to an end of adelivery hose which in turn is coupled to a source (both of which arenot shown) of cryogenic media. A threaded portion 72 of the fitting isformed for removable mounting to the delivery hose and further providescommunication with the cryogenic media for both delivery to and exhaustfrom the probe.

As shown in FIG. 6, each probe includes an elongated shaft 66sufficiently dimensioned and shaped to enable manual manipulation of theablating end 70 into contact with the desired heart tissue from outsidethe thoracic cavity. The shaft 66 is preferably tubular-shaped anddefines a communication passageway 73 extending therethrough whichprovides both delivery and exhaust of the cryogen to and from theablating end 70. Communication passageway 73 extends fully from thefitting 71 (FIG. 4) to a closed-end boiler chamber 75 where the cryogenexits the ablating end 70. Preferably, the tubular shaft 66 includes anouter diameter in the range of about 2.0 mm to about 5.0 mm, and mostpreferably about 4.0 mm; while the inner diameter is in the range ofabout 1.5 mm to about 4.5 mm, and most preferably about 3.0 mm.

Concentrically positioned in the communication passageway 73 of eachprobe is a delivery tube 76 (FIG. 6) which extends from the fitting 71to proximate the boiler chamber 75 for communication therebetweenenabling delivery and dispersion of the cryogen to the boiler chamber.The proximal end of delivery tube 76 is coupled to the cryogen liquidsource through a conventional fitting for delivery of the cryogenthrough a delivery passageway 77. The outer diameter of delivery tube 76is dimensioned such that an annular exhaust passageway 78 is formedbetween the outer diameter of the delivery tube 76 and the innerdiameter of the tubular shaft 66. This exhaust passageway 78 provides aport through which the expended cryogen exiting the boiler chamber canbe exhausted. Preferably, the delivery tube 76 includes an outerdiameter in the range of about 1.4 mm to about 3.0 mm, and mostpreferably about 2.0 mm; while the inner diameter is in the range ofabout 1.15 mm to about 2.75 mm, and most preferably about 1.50 mm.

The shaft of each probe 56 is specifically formed and shaped tofacilitate performance of one or more of the particular procedures to bedescribed in greater detail below. However, due to the nature of theprocedure and the slight anatomical differences between patients, eachprobe may not always accommodate a particular patient for the designatedprocedure. Accordingly, it is highly advantageous and desirable toprovide an exhaust shaft 66 and delivery tube 76 combination which ismalleable. This material property permits reshaping and bending of theexhaust shaft and delivery tube as a unit to reposition the ablatingsurface for greater ablation precision. Moreover, the shaft must becapable of bending and reshaping without kinking or collapsing. Suchproperties are especially imperative for the devices employed in thepulmonary vein isolation lesion formation which are particularlydifficult to access.

This malleable material, for example, may be provided by certainstainless steels, NiTi or a shape memory alloy in its superelastic statesuch as a superelastic alloy. Moreover, the shaft portion, with theexception of the ablating surface, may be composed of a polymer materialsuch as plastic which of course exhibits favorable thermoplasticdeformation characteristics. Preferably, however, the exhaust anddelivery shafts 66 and 76 are composed of bright annealed 304 stainlesssteel. The delivery tube 76 may also be composed of NiTi or othersuperelastic alloy.

To prevent or substantially reduce contact between the concentric tubesduring operation, due to resonance or the like, the delivery tube 76 maybe isolated and separated from contact with the inner walls of theexhaust shaft 66 by placing spacers around the delivery tube. Thesespacers may be provided by plastic or other polymer material.Alternatively, the delivery tube may be brazed or welded to one side ofthe inner wall of the exhaust shaft 66 along the longitudinal lengththereof to resist vibrational contact, as illustrated in FIG. 8.

In accordance with the present invention, the lesions formed by thissystem and procedure are generally elongated in nature. The ablating end70 is thus provided by an elongated ablating surface 65 which extendsrearwardly from the distal end a distance of at least about seven (7)times to about thirty (30) times the outer diameter of the ablating end,which incidentally is about the same as the outer diameter of the shaft66. Hence, the length of the ablating surface is at least three (3) cmlong, more preferably at least four (4) cm long, and most preferably atleast five (5) cm long. Alternatively, the ablating surface 65 has alength of between about three (3) cm to about eight (8) cm.

In most applications, uniform cryothermic cooling along the full lengthof the ablating surface is imperative for effective operation. Thistask, alone, may be difficult to accomplish due primarily to therelatively small internal dimensions of the probe, as well as thegenerally curved nature of the boiler chambers in most of the cryoprobes(FIG. 4). FIG. 6 represents a typical cross-sectional view of anablating end 70 of one of the probe devices of the present invention inwhich the ablating surface 65 is formed to contact the heart tissue forlocalized, transmural ablation thereof. Ablating end 70 therefore ispreferably provided by a material exhibiting high thermal conductivityproperties suitable for efficient heat transfer during cryogenic coolingof the tip. Such materials preferably include silver, gold and oxygenfree copper or the like.

The ablating end 70 is preferably provided by a closed-end, elongatedtube having an interior wall 80 which defines the boiler chamber 75, andis about 1.0 mm to about 1.5 mm thick, and most preferably about 1.25 mmthick. This portion is specifically shaped for use in one or moreablation procedures and is formed for penetration through the muscularwalls of the heart. The distal end of exhaust shaft 66 is preferablyinserted through an opening 81 into the boiler chamber 75 such that theexterior surface 82 at the tip of the exhaust shaft 66 seatably abutsagainst the interior wall 80 of the ablating end 70 for mountingengagement therebetween. Preferably, silver solder or the like may beapplied to fixably mount the ablating end to the end of the exhaustshaft. Alternatively, the proximal end of ablating end 70 can be mounteddirectly to the distal end of exhaust shaft 66 (i.e., in an end-to-endmanner) using electron-beam welding techniques. In either mountingtechnique, a hermetic seal must be formed to eliminate cryogen leakage.

Proximate the distal end of delivery tube 76 is a delivery portion 83which extends through the opening 81 and into boiler chamber 75 of theablating end 70. This closed-end delivery portion includes a pluralityof relatively small diameter apertures 85 which extend through thedelivery portion 83 into delivery passageway 77 to communicate thepressurized cryogen between the delivery passageway and the boilerchamber 75. Using the Joule-Thompson effect, the cryogen flows throughthe delivery passageway in the direction of arrow 86 and into thedelivery portion 83 where the cryogen expands through the apertures fromabout 600-900 psi to about 50-200 psi in the boiler chamber. As thecryogen expands, it impinges upon the interior wall 80 of the ablatingend cooling the ablating surface 65. Subsequently, the expended cryogenflows in the direction of arrow 87 passing through the exhaustpassageway 78 and out through the delivery hose.

The number of apertures required to uniformly cool the ablating end isprimarily dependent upon the length of the boiler chamber 75, thediameter of the apertures, the type of cryogen employed and the pressureof the cryogen. Generally, for the preferred cryogen of nitrous oxide(N₂ O), these delivery apertures 85 are equally spaced-apart at about 5mm to about 12 mm intervals, and extend from the proximal end of theboiler chamber to the distal end thereof. The preferred diameters of theapertures 85 range from about 0.004 inch to about 0.010 inch. Thesediameters may vary of course.

For most probes, three to four apertures or sets of aperturesspaced-apart longitudinally along delivery end portion are sufficient.Only one aperture 85 may be required at each longitudinal spacedlocation along the delivery portion 83 (FIG. 8). This one aperture maybe strategically positioned radially about the delivery portion todirect the stream of cryogen onto the portion of the interior wall 80directly beneath or near the predetermined portion of the ablatingsurface 65 which is to contact the heart wall tissue for a particularprocedure. Hence, the spaced-apart apertures may be strategicallypositioned to collectively direct the cryogen onto particular surfacesof the ablating end to assure maximum cooling of those portions. In someinstances, however (as shown in FIG. 7), more than one aperture 85 maybe radially positioned about the delivery portion 83 at any onelongitudinal spaced location, proximate a plane extending transverselytherethrough, for additional cryogenic cooling of the ablating surface.This may be especially important where the probe is to be employed inmore than one procedure.

Due to the elongated and curved nature of the ablating surface 65, it isdifficult to maintain a generally uniform temperature gradient along thedesired portions of the ablating surface during cryogenic cooling. Thismay be due in part to the pressure decrease in the delivery passageway77 of the delivery portion 83 as the cryogen passes therethrough. Tocompensate for this pressure loss as the cryogen passes through thedelivery portion, the diameters of the apertures 85, 85', 85" etc., maybe slightly increased from the proximal end of the delivery portion 83to the distal end thereof. Thus, as the cryogen travels through thedelivery portion 83 of the delivery tube, a more uniform volume ofcryogen may be distributed throughout the boiler chamber 75 even thoughthe cryogenic pressure incrementally decreases from the proximal end ofthe delivery portion 83.

Moreover, the delivery volume of the cyrogenic cooling also may becontrolled by varying the number of apertures at particular portions ofthe ablating end i.e., increasing or decreasing the number of aperturesat a particular location. This directed cooling will have a localizedcooling effect, and is exemplified in the ablating end 70 of FIG. 4. Inthis embodiment, the increased number of apertures along the inner bightportion 88 of delivery portion 83 delivers a more direct and greatervolume of cryogen against the inner bight portion 88, as compared to theouter bight portion 90.

An insulative coating or tubing 89 is preferably included extendingcircumferentially around portions of the cryoprobe shaft 66 near theablation end 70. This insulative tubing provides an insulatory barrieraround shaft 66 to prevent inadvertent direct contact between the shaft,which will be cooled by the expended cryogen flowing through the exhaustpassageway 75, and any organs or tissue of the percutaneous penetration.The insulative tubing is preferably spaced from the shaft 66 to definean air gap between the inner surface of the tubing and the outer surfaceof the shaft.

The insulative tubing 89 preferably extends around the elongated shaft66 from the base of the ablation end 70 to the fitting 71. In someinstances, however, the tubing may only need to extend from the base ofthe ablation end to a midportion of the elongated shaft. The insulativetubing 89 is preferably provided by heat shrink polyolefin tubing,silicone, TEFLON®, or the like.

In the preferred form, as shown in FIG. 7, the transverse,cross-sectional dimension of the ablating end 70 is circular-shapedhaving a substantially uniform thickness. However, it will be understoodthat the ablating surface 65 may include a generally flat contactsurface 91 formed for increased area contact with the heart tissuewithout requiring a substantial increase in the diameter of the ablatingsurface. As best viewed in FIGS. 8A-8C, contact surface 91 may begenerally flat or have a much larger radius than that of the ablatingend. Moreover, the spaced-apart apertures 85 are preferably oriented andformed to deliver the cryogen into direct impingement with the undersideof the contact surface 91 of ablating end 70. In this arrangement, thedelivery portion 83 of the delivery tube 76 may be mounted to one sideof the interior wall 80, as set forth above.

Alternatively, the contact surface can be provided by a blunted edge orthe like to create a relatively narrow lesion. Although not illustrated,the transverse cross-sectional dimension of this embodiment would appearteardrop-shaped.

FIGS. 6A-6D illustrate an embodiment of the probe 57 in which aninsulative jacket or sleeve 304 is disposed on the probe so as to bemovable relative thereto. The sleeve 304 has a window or cut-out portion305 which exposes a selected area of the probe 57. FIG. 6A shows thesleeve 304 located around the probe shaft, while FIG. 6B shows thesleeve after it has been slid over part of the probe ablating surface65. FIG. 6C shows the sleeve 304 after it has been slid completely overthe ablating surface 65 to a position where the window 305 exposes onearea of the surface 65 for ablating tissue. FIG. 6D shows the sleeve 304rotated to a different position where the window 305 exposes a differentarea of the surface 65 for ablating tissue. The sleeve 304 may beslidable and rotatable relative to the probe as show in FIGS. 6A-6D.Alternatively, the sleeve 304 may be fixed axially with respect to theprobe 57 but rotatable relative thereto so that the window is able toexpose different areas of the ablating surface. Further still, thesleeve 304 may be fixed on the probe 57 such that only a selected areaof ablation surface 65 is exposed through window 305. The sleeve 304 maybe formed of any suitable material, for example, a flexible polymerhaving low thermal conductivity.

The preferred cryogen employed in the devices of the present inventionis nitrous oxide (N₂ O) which is normally stored in a compressed gascylinder (not shown). Other cryogenic fluids may be employed whichinclude liquid nitrogen or liquified air stored in a Dewar vessel (notshown), freon 13, freon 14, freon 22, and normally gaseous hydrocarbons.

To cool the ablating end of the cryoprobe, cryogen is selectivelydelivered through the delivery passageway 77 of delivery tube 76 intothe delivery conduit thereof. As the cryogen flows through deliveryapertures 85, the gas expands into the boiler chamber 75, cooling theablating surface using the well known Joule-Thompson effect. Theelongated ablating surface 65 is then immediately cooled to atemperature of preferably between about -50° C. to about -80° C., whennitrous oxide is employed. Direct conductive contact of the cooled,elongated ablating surface 65 with the selected heart tissue causescryogenic ablation thereof. Subsequently, a localized, elongated,transmural lesion is formed at a controlled location which sufficientlyprevents or is resistant to electrical conduction therethrough.

To assure preclusion of electrical conduction of reentrant pathways inthe atria, the lesions must be transmural in nature. Hence, the minimumlength of time for conductive contact of the ablating surface with theselected heart tissue necessary to cause localized, transmural ablationthereof is to a large degree a function of the thickness of the heartwall tissue, the heat transfer loss due do the convective and conductiveproperties of the blood in fluid contact with the ablating surface, aswell as the type of cryogen employed and the rate of flow thereof. Inmost instances, when employing nitrous oxide as the cryogen, tissuecontact is preferably in the range of about 2-4 minutes.

As mentioned, while the closed-heart surgical system and procedure ofthe present invention may be performed through open-chest surgery, thepreferred technique is conducted through closed-chest methods. FIGS. 5and 9 illustrate system 56 for closed-chest, closed-heart surgerypositioned in a patient P on an operating table T. The patient isprepared for cardiac surgery in the conventional manner, and generalanesthesia is induced. To surgically access the right atrium, thepatient is positioned on the patient's left side so that the rightlateral side of the chest is disposed upward. Preferably, a wedge orblock W having a top surface angled at approximately 20° to 45° ispositioned under the right side of the patient's body so that the rightside of the patient's body is somewhat higher than the left side. Itwill be understood, however, that a similar wedge or block W ispositioned under the left side of patient P (not shown) when performingthe surgical procedure on the left atrium In either position, thepatient's right arm A or left arm (not shown) is allowed to rotatedownward to rest on table T, exposing either the right lateral side orthe left lateral side of the patient's chest.

Initially one small incision 2-3 cm in length is made between the ribson the right side of the patient P, usually in the third, fourth, orfifth intercostal spaces, and most preferably the fourth as shown inFIG. 11A. When additional maneuvering space is necessary, theintercostal space between the ribs may be widened by spreading of theadjacent ribs. A thoracoscopic access device 68 (e.g. a retractor,trocar sleeve or cannulae), providing an access port 67, is thenpositioned in the incision to retract away adjacent tissue and protectit from trauma as instruments are introduced into the chest cavity. Thisaccess device 68 has an outer diameter preferably less than 14 mm and anaxial passage of a length less than about 12 mm. It will be understoodto those of ordinary skill in the art that additional thoracoscopictrocars or the like may be positioned within intercostal spaces in theright lateral chest inferior and superior to the retractor 68, as wellas in the right anterior (or ventral) portion of the chest if necessary.In other instances, instruments may be introduced directly throughsmall, percutaneous intercostal incisions in the chest.

Referring again to FIGS. 5 and 9, the retractor 68, such as thatdescribed in detail in commonly assigned U.S. patent application Ser.No. 08/610,619 filed Mar. 4, 1996, surgical access to the body cavity ofpatient P through the first intercostal percutaneous penetration 92 inthe tissue 93. Briefly, retractor 68 includes an anchoring frame 95having a passageway 67 therethrough which defines a longitudinalretractor axis. The anchoring frame 95 is positionable through theintercostal percutaneous penetration 92 into the body cavity. A flexibletensioning member 96 is attached to anchoring frame 95 and extendiblefrom the anchoring frame out of the body through intercostal penetration92 to deform into a non-circular shape when introduced between two ribs.The tensioning member 96 is selectively tensionable to spread the tissueradially outward from the longitudinal axis. Hence, it is the tensionimposed on the flexible tensioning member 96 which effects retraction ofthe tissue, rather than relying on the structural integrity of a tubularstructure such as a trocar sheath.

Once the retractor 68 has been positioned and anchored in the patient'schest, visualization within the thoracic cavity may be accomplished inany of several ways. An endoscope 97 (FIG. 5) of conventionalconstruction is positioned through a percutaneous intercostalpenetration into the patient's chest, usually through the port of thesoft tissue retractor 68. A video camera 98 is mounted to the proximalend of endoscope 97, and is connected to a video monitor 100 for viewingthe interior of the thoracic cavity. Endoscope 97 is manipulated so asto provide a view of the right side of the heart, and particularly, aright side view of the right atrium. Usually, an endoscope of the typehaving an articulated distal end such as the Distalcam 360, availablefrom Welch-Allyn of Skameateles Falls, N.Y., or a endoscope having adistal end disposed at an angle between 30 and 90 will be used, which iscommercially available from, for example, Olympus Corp., MedicalInstruments Division, Lake Success, N.Y. A light source (not shown) isalso provided on endoscope 97 to illuminate the thoracic cavity.

Further, the surgeon may simply view the chest cavity directly throughthe access port 67 of the retractor 68. Moreover, during the closedheart procedure of the present invention, it may be desirable tovisualize the interior of the heart chambers. In these instances atransesophageal echocardiography may be used, wherein an ultrasonicprobe is placed in the patient's esophagus or stomach to ultrasonicallyimage the interior of the heart. A thoracoscopic ultrasonic probe mayalso be placed through access device 68 into the chest cavity andadjacent the exterior of the heart for ultrasonically imaging theinterior of the heart.

An endoscope may also be employed having an optically transparent bulbsuch as an inflatable balloon or transparent plastic lens over itsdistal end which is then introduced into the heart. As disclosed incommonly assigned, co-pending U.S. patent application Ser. No.08/425,179, filed Apr. 20, 1995, the balloon may be inflated with atransparent inflation fluid such as saline to displace blood away fromdistal end and may be positioned against a site such a lesion, allowingthe location, shape, and size of cryolesion to be visualized.

As a further visualization alternative, an endoscope may be utilizedwhich employs a specialized light filter, so that only those wavelengthsof light not absorbed by blood are transmitted into the heart. Theendoscope utilizes a CCD chip designed to receive and react to suchlight wavelengths and transmit the image received to a video monitor. Inthis way, the endoscope can be positioned in the heart through accessport 67 and used to see through blood to observe a region of the heart.A visualization system based on such principles is described in U.S.Pat. No. 4,786,155, which is incorporated herein by reference.

Finally, the heart treatment procedure and system of the presentinvention may be performed while the heart remains beating. Hence, thetrauma and risks associated with cardiopulmonary bypass (CPB) andcardioplegic arrest can be avoided. In other instances, however,arresting the heart may be advantageous. Should it be desirable to placethe patient on cardiopulmonary bypass, the patient's right lung iscollapsed and the patient's heart is arrested. Suitable techniques forarresting cardiac function and establishing CPB without a thoracotomyare described in commonly-assigned, co-pending U.S. patent applicationSer. No. 08/282,192, filed Jul. 28, 1994 and U.S. patent applicationSer. No. 08/372,741, filed Jan. 17, 1995, all of which are incorporatedherein by reference. Although it is preferred to use the endovascularsystems described above, any system for arresting a patient's heart andplacing the patient on CPB may be employed.

As illustrated in FIG. 10, CPB is established by introducing a venouscannula 101 into a femoral vein 102 in patient P to withdrawdeoxygenated blood therefrom. Venous cannula 101 is connected to acardiopulmonary bypass system 104 which receives the withdrawn blood,oxygenates the blood, and returns the oxygenated blood to an arterialreturn cannula 105 positioned in a femoral artery 106.

A pulmonary venting catheter 107 may also be utilized to withdraw bloodfrom the pulmonary trunk 108. Pulmonary venting catheter 107 may beintroduced from the neck through the interior jugular vein 110 andsuperior vena cava 111, or from the groin through femoral vein 102 andinferior vena cava 103. An alternative method of venting blood frompulmonary trunk 108 is described in U.S. Pat. No. 4,889,137, which isincorporated herein by reference. In the technique described therein, anendovascular device is positioned from the interior jugular vein in theneck through the right atrium, right ventricle, and pulmonary valve intothe pulmonary artery so as to hold open the tricuspid and pulmonaryvalves.

For purposes of arresting cardiac function, an aortic occlusion catheter113 is positioned in a femoral artery 106 by a percutaneous techniquesuch as the Seldinger technique, or through a surgical cut-down. Theaortic occlusion catheter 113 is advanced, usually over a guidewire (notshown), until an occlusion balloon 115 at its distal end is disposed inthe ascending aorta 116 between the coronary ostia and thebrachiocephalic artery. Blood may be vented from ascending aorta 116through a port 120 at the distal end of the aortic occlusion catheter113 in communication with an inner lumen in aortic occlusion catheter113, through which blood may flow to the proximal end of the catheter.The blood may then be directed to a blood filter/recovery system 121 toremove emboli, and then returned to the patient's arterial system viaCPB system 104.

When it is desired to arrest cardiac function, occlusion balloon 115 isinflated until it completely occludes ascending aorta 116, blockingblood flow therethrough. A cardioplegic fluid such as potassium chloride(KCl) is preferably mixed with oxygenated blood from the CPB system andthen delivered to the myocardium in one or both of two ways.Cardioplegic fluid may be delivered in an anterograde manner, retrogrademanner, or a combination thereof. In the anterograde delivery, thecardioplegic fluid is delivered from a cardioplegia pump 122 through aninner lumen in aortic occlusion catheter 113 and the port 120 distal toocclusion balloon 115 into the ascending aorta upstream of occlusionballoon 115. In the retrograde delivery, the cardioplegic fluid may bedelivered through a retroperfusion catheter 123 positioned in thecoronary sinus from a peripheral vein such as an internal jugular veinin the neck.

With cardiopulmonary bypass established, cardiac function arrested, andthe right lung collapsed, the patient is prepared for surgicalintervention within the heart H. At this point in the procedure, whethercardiac function is arrested and the patient is placed on CPB, or thepatient's heart remains beating, the heart treatment procedure andsystem of the present invention remain substantially similar. Theprimary difference is that when the procedure of the present inventionis performed on an arrested heart, the blood pressure in the internalchambers of the heart is significantly less. Hence, it is not necessaryto form a hemostatic seal between the device and the heart wallpenetration to inhibit blood loss through the penetration therebyreducing or eliminating the need for purse-string sutures around suchpenetrations, as will be described below.

In the preferred embodiment, however, the procedure is conducted whilethe heart is still beating. Accordingly, it is necessary to form ahemostatic seal between the ablation device and the penetration.Preferably, purse-string sutures 58, 60, 61, 62 and 63 (FIGS. 3A and 3B)are placed in the heart walls at strategic or predetermined locations toenable introduction of the ablating probes into the heart whilemaintaining a hemostatic seal between the probe and the penetration.

As best viewed shown in FIG. 11A, in order to gain access to the rightatrium of the heart, a pericardiotomy is performed using thoracoscopicinstruments introduced through retractor access port 67. Instrumentssuitable for use in this procedure, including thoracoscopic angledscissors 130 and thoracoscopic grasping forceps 131, are described incommonly assigned U.S. Pat. No. 5,501,698, issued Mar. 26, 1996, whichis incorporated herein by reference.

After incising a T-shaped opening in the pericardium 132 (about 5.0 cmin length across and about 4.0 cm in length down, FIG. 11A), theexterior of the heart H is sufficiently exposed to allow theclosed-chest, closed-heart procedure to be performed. To further aid invisualization and access to the heart H, the cut pericardial tissue 133is retracted away from the pericardial opening 135 with stay sutures 136(FIG. 11C) extending out of the chest cavity. This technique allows thesurgeon to raise and lower the cut pericardial wall in a manner whichreshapes the pericardial opening 135 and retracting the heart Hslightly, if necessary, to provide maximum access for a specificprocedure.

To install stay suture 136, a curved suture needle 137 attached to oneend of a suture thread 138 is introduced into the chest cavity throughpassageway 67 with of a thoracoscopic needle driver 140 (FIG. 11B). Oncethe suture needle 137 and thread 138 have been driven through the cutpericardial tissue, the suture thread 138 is snared by a suture snaredevice 141. This is accomplished by positioning a hooked end 142 ofsuture snare device 141 through at least one additional percutaneousintercostal penetration 143 positioned about the chest to enablepenetration into the thoracic cavity. In the preferred arrangement, atrocar needle (not shown) is employed which not only forms thepenetration, but also provides access into the thoracic cavity withoutsnaring tissue during removal of the snare device.

Accordingly, both sides of the suture thread 138 are snared and pulledthrough the chest wall for manipulation of the stay suture from outsideof the body cavity. The ends of the stay suture 136 are coupled to asurgical clamp (not shown) for angled manipulation and tensionadjusting. While only two stay sutures are illustrated, it will beappreciated that more stay sutures may be employed as needed to furthermanipulate the pericardial opening.

Turning now to FIG. 11C, a first 4-0 purse-string suture 58, forexample, is placed in the heart wall proximate the site at which it isdesired to initiate the first heart wall penetration 146 (FIG. 11D).Again, this is accomplished by using a thoracoscopic needle driver todrive the suture needle through the heart wall to form a running stitchin a circular pattern approximately 1.0-3.0 mm in diameter. Adouble-armed suture may also be used, wherein the suture thread 145(about 3 mm to about 10 mm in diameter) has needles (not shown) at bothends, allowing each needle to be used to form one semi-circular portionof the purse-string. Suture thread 138 is long enough to allow both endsof the suture to be drawn outside of the chest cavity once purse-stringsuture 58 has been placed. The suture needle is then cut from thread 145using thoracoscopic scissors.

To tension the purse-string suture 58, the suture threads 145 are pulledupon gathering the stitched circular pattern of tissue together beforecommencement of the formation of a penetration through the heart wallwithin the purse-string suture. One or a pair of thoracoscopic cinchinginstruments 147, such as a Rumel tourniquet, may be employed to grasp aloop of purse-string suture 58. As best viewed in FIG. 11D, cinchinginstrument 147 comprises a shaft 148 with a slidable hook 150 at itsdistal end thereof for this purpose. Hook 150 may be retractedproximally to frictionally retain suture thread 145 against the distalend of shaft 148. By retracting or withdrawing the cinching instrument147, the purse-string suture 58 is cinched tightly, thereby gatheringheart wall tissue together to form a hemostatic seal.

The cinching instrument may be clamped in position to maintain tensionon suture thread 145. Preferably, however, a slidable tensioning sleeve151 (FIG. 11D), commonly referred to as a snugger, may be provided inwhich the suture threads are positioned through a bore extendingtherethrough. The snugger is then slid along the suture thread until itabuts against the epicardial surface 152 of the heart wall. The cinchinginstrument is then pulled proximally relative to tensioning sleeve 151to obtain the desired degree of tension on suture thread 145. Tensioningsleeve 151 is configured to frictionally couple to suture thread 145 tomaintain tension on the suture.

An incision device 153 is introduced through access device 68 into thechest cavity for piercing the heart H. A blade 155 positioned on thedistal end of a manipulating shaft 156 is advanced to pierce the heartwall within the bounds of purse-string suture 58. The blade 155 ispreferably about 5.0 mm in length and about 3.0 mm wide terminating atthe tip thereof. FIG. 11D illustrates that as the incision device 153 ismanually moved further into contact with the epicardial surface 152 ofthe heart wall, blade 155 will be caused to pierce therethrough to forma penetration of about 1.0-2.0 mm across.

In the preferred form, the blade 155 is rigidly mounted to shaft 156 fordirect one-to-one manipulation of the blade. Alternatively, however, theincision device may employ a spring loaded mechanism or the like whichadvances the blade forwardly from a retracted position, retracted in aprotective sleeve of the shaft, to an extended position, extending theblade outside of the sleeve and into piercing contact with the tissue.In this embodiment, a button or the like may be provided near theproximal end of the shaft for operation of the blade between theretracted and extended positions.

To facilitate formation of the penetration by the incision device, athoracoscopic grasping instrument (not shown) may be employed to graspthe heart wall near purse-string suture 58 to counter the insertionforce of blade 155 and incision device 153. As blade 155 penetrates theheart wall, incision device 153 is advanced to extend transmurally intothe heart through the penetration 146 formed in heart wall.

As above-indicated in FIGS. 3A and 3B, the entire procedure ispreferably performed through a series of only five purse-strings sutures58, 60, 61, 62 and 63, and the corresponding cardiac penetrations 146,157, 158, 160 and 161 of which two penetrations 158, 160 arestrategically positioned in the right atrium RA; one penetration 161 ispositioned in the left atrium LA; and two penetrations 158, 160 arepositioned near the pulmonary vein trunk 108. Such small incisions aresignificantly less traumatic on the heart tissue muscle than theelongated transmural incisions of the prior MAZE techniques.

Referring now to FIGS. 3A, 12A-12C and 13, the system and procedure ofthe present invention will be described in detail. Preferably, the firstseries of lesions is formed on the right atrium RA to form a posteriorlongitudinal right atrial lesion 50 and a tricuspid valve annulus lesion51. It will be appreciated, however, that the transmural lesions can beformed in any order without departing from the true spirit and nature ofthe present invention.

By strategically placing the first heart wall penetration 146 of firstpurse-string suture 58 at the base of the right atrial appendage RAAwhere the anticipated intersection between the longitudinal right atriallesion 50 and the tricuspid valve annulus lesion 51 are to occur (FIG.12C), these two lesions can be formed through a series of threeindependent ablations. As best viewed in FIG. 12A, the upper sectionsegment 162 (half of the longitudinal right atrial lesion 50) is formedusing a right angle probe 163 (FIG. 24) having a first elbow portion 166positioned between the generally straight elongated shaft 66 and thegenerally straight ablating end. The first elbow portion has an arclength of about 85° to about 95° and a radius of curvature of about 3.2mm to about 6.4 mm. The ablating end 70 is preferably about 2.0 mm toabout 4.0 mm in diameter, and about 2.0 cm to about 6.0 cm in length. Inthis configuration, the ablating surface 65 extends, circumferentially,from a distal end 165 thereof to just past an elbow portion 166 of theright angle probe 163.

Initially, the probe ablating end 70 and the shaft 66 of probe 163 isintroduced into the thoracic cavity through the retractor 68 bymanipulating a handle (not shown) releasably coupled to fitting 71. Tofacilitate location of the first penetration with the probe, the distalend 165 is guided along the shaft 156 of incision device 153 (FIG. 11D)until positioned proximate the first penetration 146. Subsequently, theblade 155 of incision device is withdrawn from the first penetrationwhereby the distal end of the probe is immediately inserted through thefirst penetration. Not only does this technique facilitate insertion ofthe probe but also minimizes loss of blood through the penetration.

Once the distal end 165 of the right angle probe 163 has been insertedand negotiated through the first penetration, the first purse-stringsuture may require adjustment to ensure the formation of a properhemostatic seal between the penetration and the shaft of the probe. Ifthe loss of blood should occur, the purse-string suture can be easilytightened through either a Rumel tourniquet or tensioning sleeve 151.

FIG. 12A best illustrates that the right angle probe 163 is preferablyinserted through the penetration 146 until an elbow portion 166 thereofjust passes through the penetration. Although the angular manipulationof the end of the right angle probe is limited due to the accessprovided by the retractor, the insertion should be easily accommodatedsince the heart wall tissue of the right atrium is substantiallyresilient and flexible. Again, a thoracoscopic grasping instrument (notshown) may be employed to grasp the heart wall near the firstpurse-string suture 58 to counter the insertion force of right angleprobe 163 through the first penetration 146. Once the ablating end isinserted to the desired depth and through the assistance of eitherdirect viewing or laparoscopic viewing, the elongated ablating end 70 isoriented to position a longitudinal axis thereof generally parallel tothe right atrioventricular groove. This upper section segment 162 of thelongitudinal right atrial lesion 50 extends generally from the firstpenetration 146 to the orifice of the superior vena cava 111. Byretracting the probe rearwardly out of the passageway of the retractor68 generally in the direction of arrow 167, the ablating surface will becaused to sufficiently contact the right atrial endocardium.

As mentioned above, the probe may use any method to ablate the hearttissue. When using a cryogenic ablating system, the cryogen stored in aDewar vessel or pressurized cylinder is selectively released where itpasses into the boiler chamber 75 of the device 163, thereby cooling theprobe ablating surface for localized ablation of heart tissue. Aspreviously stated, to warrant proper transmural ablation of the interiorwall of the right atrium, continuous contact of the ablating surfacetherewith should occur for about 2-4 minutes. Visually, however,transmural cryosurgical ablation of the tissue is generally representedby a localized lightening or discoloration of the epicardial surface 168of the ablated heart tissue which can be directly viewed through theaccess port 67 of access device 68. This method of determiningcryoablation of the tissue can be used in combination with the timedprobe contact therewith. As a result, the upper section segment 162 ofthe longitudinal right atrial lesion 50 will be formed.

Once the desired elongated portion of heart tissue has been ablated,caution must be observed before the ablating surface 65 probe can beseparated from the contacted endocardial surface of the heart tissue.Due to the extremely low temperatures of the ablating surface (i.e.,about -50° to about -80°) and the moistness of the heart tissue,cryoadhesion can occur. Accordingly, the probe tip must be properlythawed or defrosted to enable safe separation after the tissue has beenproperly ablated.

For example, after sufficient transmural cryoablation of the hearttissue, thawing is commenced by halting the flow of cryogen through theprobe and maintaining continuous contact between the probe ablatingsurface and the cryoablated tissue. After about 10-20 seconds, andpreferably about 15 seconds, the conductive and convective heat transferor heat sink effect from the surrounding tissue and blood is sufficientto reverse the cryoadhesion. Of course, it will be appreciated that suchheat transfer is more efficient when the procedure is performed on abeating heart as opposed to an arrested heart. Alternatively, the systemmay also be provided with a defrost mode which serves to warm the tissueto room temperature. This may be accomplished by raising the pressure ofthe cryogen adjacent the ablating surface such that its temperatureincreases, for example, by restricting the exhaust gas flow.

Furthermore, to facilitate thawing of the exterior surface of theablated tissue, a room temperature or slightly heated liquid may bewetted or impinged upon the exterior surface of the ablated area. In thepreferred embodiment, such liquid may include saline or other non-toxicliquid introduced into the thoracic cavity through the retractorpassageway 67.

Generally, multiple lesions can be formed through a single purse-stringsuture either through the use of assorted uniquely shaped ablatingdevices or through the manipulation of a single ablating device.Accordingly, while maintaining the hemostatic seal between the probeshaft and the penetration, the respective ablating device can bemanipulated through the respective penetration to strategically contactthe corresponding elongated ablating surface with another selectedportion of the interior surface of the muscular wall for transmuralablation thereof. For instance, without removing the right anglecryoprobe from the first penetration, the ablating surface 65 is rotatedapproximately 1800 about the longitudinal axis to re-position the distalend generally in a direction toward the orifice of the inferior venacava 103. As shown in FIG. 12B, such positioning enables the formationof the remaining lower section segment 170 of the longitudinal rightatrial lesion 50. However, since the lower section segment 170 of thelesion is shorter in length than that of the upper section segment, thelength of the elongated ablating surface contacting the interior wall ofright atrium must be adjusted accordingly. This length adjustment isaccomplished by partially withdrawing the probe ablating surface 65 fromthe first penetration 146 by the appropriate length to ablate the lowersection segment 170. Due to the substantial flexibility and resiliencyof the heart tissue, such maneuverability of the probe and manipulationof the tissue is permissible.

Similar to the formation of the upper section segment 162 of thelongitudinal right atrial lesion 50, the right angle probe 163 isretracted rearwardly, generally in the direction of arrow 167, causingthe ablating surface 65 of the probe to sufficiently contact theendocardium of the right atrium. After the cryogen has continuouslycooled the elongated ablating surface 65 of the probe for about 2-4minutes, the remaining lower section segment of the longitudinal rightatrial lesion 50 will be formed. Thereafter, the probe is defrosted toreverse the effects of cryoadhesion. It will be understood that while itis beneficial to employ the same right angle probe to perform both theupper and lower section segments of the longitudinal right atriallesion, a second right angle probe having an ablating surface shorter inlength than that of the first right angle probe could easily beemployed.

Utilizing the same first penetration, the tricuspid valve annulus lesion51 can be formed employing one of at least two probes. Preferably, theright angle probe 163 may again be used by rotating the elongatedablating surface 65 about the probe shaft longitudinal axis toreposition the distal end trans-pericardially, generally in a directionacross the lower atrial free wall and toward the tricuspid valve 171(FIGS. 12C and 13). The distal end of the probe ablating surface 65,however, must extend all the way to the tricuspid valve annulus 172.Hence, in some instances, due to the limited maneuvering space providedthrough the retractor passageway, the formation of the tricuspid valveannulus lesion 51 with the right angle probe may be difficult toperform.

In these instances, a special shaped tricuspid valve annulus probe 173(FIGS. 13 and 25) is employed which is formed and dimensioned to enablecontact of the probe ablating surface 65 with appropriate portion of theright atrium interior wall all the way from the first penetration 146 tothe tricuspid valve annulus 172 to form the tricuspid valve annuluslesion 51. The ablating end 70 and the shaft 66 of this probe cooperateto form one of the straighter probes 57 of the set shown in FIG. 4.

FIG. 25 best illustrates the tricuspid valve annulus probe 173 whichincludes an elongated shaft 66 having a first elbow portion 166positioned between a generally straight first portion 175 and agenerally straight second portion 176 having a length of about 2.0 cm toabout 6.0 cm. The first elbow portion has an arc length of about 20° toabout 40° and a radius of curvature of about 13.0 cm to about 18.0 cm.Further, a second elbow portion 177 is positioned between the secondportion 176 and a third portion 178 of the shaft, angling the thirdportion back toward the longitudinal axis of the first portion 175 ofthe elongated shaft 66. The third portion 178 includes a length of about2.0 cm to about 6.0 cm, while the second elbow portion has an arc lengthof about 5° to about 20° and a radius of curvature of about 15.0 cm toabout 20.0 cm. The ablating end 70 is relatively straight and is coupledto the distal end of the third portion 178 of the elongated shaft 66 ina manner angling the ablating end back away from the longitudinal axisand having an arc length of about 5° to about 20° and a radius ofcurvature of about 13.0 cm to about 18.0 cm. The ablating end 70 isformed to extend from the first penetration and to the rim 172 of thetricuspid valve 171 from outside of the body cavity. For this probe, theablating surface 65 is preferably about 2.0 cm to about 6.0 cm inlength. It will be understood that while the illustrations anddescriptions of the probes are generally two dimensional, theconfigurations of the shaft and ablating end combinations could be threedimensional in nature.

Using the insertion technique employed by the right angle probe 163during the formation of the longitudinal right atrial lesion 50, uponwithdrawal of the right angle probe from the first penetration 146, thedistal end of the tricuspid valve annulus probe 173 is immediatelyinserted therethrough to facilitate alignment and minimize the loss ofblood.

Regardless of what instrument is employed, once the probe ablatingsurface 65 is strategically oriented and retracted to contact theendocardial surface, the cryogen is selectively released into the boilerchamber to subject the desired tissue to localized cryothermia. Due tothe nature of the transmural ablation near the tricuspid valve annulus,the need for dividing all atrial myocardial fibers traversing theablated portion is effectively eliminated. Thus, the application of thenerve hook utilized in the prior MAZE procedures is no longer necessary.

As illustrated in FIG. 13, the distal end of the probe must extend tothe base of the tricuspid valve annulus 172. This lesion is difficult tocreate since the right atrial free-wall in this region lies beneath theatrioventricular groove fat pad (not shown). To facilitate orientationof the ablating end of the probe relative the valve annulus and tobetter assure the formation of a lesion which is transmural in nature,an alternative tricuspid valve clamping probe 180 (FIG. 26) may beemployed rather than or in addition to the tricuspid valve annulus probe173.

This probe includes a primary shaft 66 and ablating end 70 which arecooperatively shaped and dimensioned substantially similar to thetricuspid valve annulus probe 173. A clamping device 181 of clampingprobe 180 includes a mounting member 179 providing an engagement slot182 formed for sliding receipt of a pin member 184 coupled to primaryshaft 66. This arrangement pivotally couples the clamping device 181 tothe primary shaft 66 for selective cooperating movement of a clampingjaw portion 183 of the clamping device 181 and the ablating end 70between a released position, separating the clamping jaw portion fromthe ablating end 70 (phantom lines of FIG. 26), and a clamped position,urging the clamping jaw portion against the ablating end 70 (solid linesof FIG. 26).

The clamping jaw portion 183 is shaped and dimensioned substantiallysimilar to the corresponding ablating end 70 to enable clamping of theheart tissue therebetween when the tricuspid valve clamping probe 180 ismoved to the clamped position. At the opposite end of the clamping jawportion 183 is a handle portion 185 for manipulation of the jaw portionbetween the released and clamped positions in a pliers-type motion.

To perform this portion of the procedure using the tricuspid valveclamping probe 180, the clamping jaw is moved toward the releasedposition to enable the distal end of the ablating end to be negotiatedthrough the first penetration 146. Using direct viewing through theretractor or visually aided with an endoscope, the ablating end is movedinto contact with the predetermined portion of the right atrium interiorwall all the way from the first penetration 146 to the tricuspid valveannulus 172. Subsequently, the clamping jaw portion is moved to theclamped position, via handle portion 185, to contact the epicardialsurface 168 of the heart wall opposite the tissue ablated by the probe.This arrangement increases the force against the ablating surface 65 tofacilitate contact and heat transfer. Cryogen is then provided to theboiler chamber to cool the ablating surface 65 thereby forming thetricuspid valve annulus lesion 51. Once the probe is removed from thefirst penetration 146, the first purse-string suture 58 is furthertightened to prevent blood loss.

The engagement slot 182 of mounting member 179 is formed to permitrelease of the pin member 184 therefrom. Hence, the clamping device 181can be released from primary shaft 66 of the clamping probe 180. Thisarrangement is beneficial during operative use providing the surgeon theoption to introduce the clamping probe 180 into the thoracic cavity asan assembled unit, or to first introduce the ablation end 70 and primaryshaft 66, and then introduce of the clamping device 181 for assemblywithin the thoracic cavity.

Turning now to FIG. 14, a second 4-0 purse-string suture 59 is placed inthe right atrial appendage RAA proximate a lateral midpoint thereof inthe same manner as above-discussed. This portion of the heart is againaccessible from the right side of the thoracic cavity through the firstaccess device 68. A second penetration 157 is formed central to thesecond purse-string suture wherein blood loss from the secondpenetration is prevented through a second tensioning sleeve 186.Subsequently, the distal end of a right angle probe or a right atriumcounter lesion probe 187 (FIGS. 15 and 27), is inserted through secondpenetration 157 and extended into the right atrial appendage chamber.Second purse-string suture 59 may then be adjusted through secondtensioning sleeve 186, as necessary to maintain a hemostatic sealbetween the penetration and the probe.

The right atrium counter lesion probe 187 includes an elongated shaft 66having a first elbow portion 166 positioned between a relativelystraight first portion 175 and a generally straight second portion 176,whereby the first elbow portion has an arc length of about 85° to about95° and a radius of curvature of about 1.9 cm to about 3.2 cm. Thesecond portion is preferably about 2.0 cm to about 6.0 cm in length.Further, a second elbow portion 177 is positioned between the secondportion 176 and a generally straight third portion 178 of the shaftwhich is about 2.0 cm to about 6.0 cm in length. The second elbowportion has an arc length of about 40° to about 70° and a radius ofcurvature of about 3.2 cm to about 5.7 cm, angling the third portion 178back toward the longitudinal axis of the first portion 175 of theelongated shaft 66. The ablating end 70 is coupled to the distal end ofthe third portion 178 of the elongated shaft 66, and includes an arclength of about 85° to about 95° and a radius of curvature of about 6.0mm to about 19.0 mm to curve the distal end thereof back toward thelongitudinal axis of the first portion 175 of the shaft 66. Thus, thisequates to an ablating surface length of preferably about 4.0 cm toabout 8.0 cm in length.

This configuration enables the ablating end 70 of probe 187 to accessthe right lateral midpoint of the atrial appendage RAA where the secondpenetration 157 is to placed. FIGS. 14 and 15 best illustrate that theposition of this second penetration 157 is higher up than the firstpenetration, relative the heart, when accessed from the predeterminedintercostal penetration 92. Upon insertion of the distal end of theprobe through the second penetration 157, the ablating end 70 isinserted into the right atrium chamber to the proper depth. The handle(not shown) of the probe 187 is manipulated and oriented from outsidethe thoracic cavity to position the distal end of the ablating surface65 in a direction generally toward the first purse-string suture 58. Theprobe is retracted rearwardly out of the retractor passageway, generallyin the direction of arrow 167 in FIG. 14, to urge the ablating surface65 of the probe into contact with the endocardial surface of theinterior wall of the right atrial appendage RAA. As a result, theperpendicular lesion 53 of the right atrial appendage is transmurallyformed.

The next lesion to be created is the anteromedial counter lesion 55which is to be formed through the second penetration 157. This lesion ispositioned just anterior to the apex of the triangle of Koch and themembranous portion of the interatrial septum. Without removing the rightatrium counter lesion probe 187 from the second penetration 157, theelongated ablating surface 65 is urged further inwardly through thesecond penetration 157 toward the rear atrial endocardium of the rightatrial appendage RAA (FIG. 15). Upon contact of the ablating surface 65with the rear atrial wall, the probe 187 is slightly rotated upwardly inthe direction of arrows 191 in FIG. 15 to exert a slight force againstthe rear endocardial surface. Again, this ensures ablative contacttherebetween to enable formation of the anteromedial counter surgicallesion 55. Subsequently, the probe is properly defrosted and withdrawnfrom the second penetration 157 whereby the second purse-string suture59 is cinched tighter to prevent blood loss therefrom. It will beunderstood that since these two lesions are formed through cryothermictechniques, the need for atrial retraction and endocardial suturingemployed in connection with the formation of the transmural incision ofthe MAZE III procedure can be eliminated.

The next step in the procedure is an atrial septotomy to from ananterior limbus of the fossa ovalis lesion 192. The formation of thislesion will likely be performed without direct or laparoscopic visualassistance since the ablation occurs along internal regions of theinteratrial septum wall 193. Initially, as best illustrated in FIGS.16-18, two side-by-side purse-string sutures 61 and 62 are surgicallyaffixed to an epicardial surface 168 proximate the pulmonary trunk 108using the same techniques utilized for the first and second purse-stringsutures. The third purse-string suture 61 is positioned on one side ofthe septum wall 193 for access to the right atrium chamber, while thefourth purse-string suture 62 is positioned on the opposite side of theseptum wall for access to the left atrium chamber.

FIG. 17 further illustrates that the introduction of thoracoscopicinstruments and access to the third and fourth purse-strings arepreferably provided through the retractor 68. After the third and fourthtensioning sleeves 195, 196 have been mounted to the respective suturethreads, an incision device (not shown) is introduced into the thoraciccavity to incise the penetrations central to the respective purse-stringsutures. Due to the angle of the upper heart tissue surface relative theretractor 68, the incision device may incorporate an angled end or bladefor oblique entry through the heart wall tissue in the direction ofarrow 197 to form the third and fourth penetrations 158, 160 (FIG. 18).Alternatively, the incision device may include a blade end which iscapable of selective articulation for pivotal movement of the blade endrelative the elongated shaft. Use of a thoracoscopic grasping instrumentfacilitates grasping of the epicardium near the pulmonary trunk 108 tocounter the insertion force of the angled blade during formation of therespective penetrations 158, 160.

To create the lesion across the anterior limbus of the fossa ovalislesion 192, a special atrial septum clamping probe 198 (FIGS. 17 and 28)is provided having opposed right angled jaw portions 200, 201 formed anddimensioned for insertion through the corresponding third and fourthpenetrations 158, 160 for clamping engagement of the anterior limbus ofthe fossa ovalis therebetween. As illustrated in FIG. 28, the atrialseptum clamping probe 198 includes a primary clamping member 202 havinga generally straight, elongated clamping shaft 66 with a first elbowportion 166 positioned between the clamping shaft 66 and a generallystraight outer jaw portion 200 (ablating end 70), whereby the firstelbow portion has an arc length of about 85° to about 95° and a radiusof curvature of about 3.2 mm to about 6.4 mm. The ablating surfaceextends just beyond elbow portion 166 and is of a length of preferablyabout 2.0 cm to about 6.0 cm.

In accordance with the special atrial septum clamping probe 198 of thepresent invention, an attachment device 203 is coupled to the clampingshaft 205 which includes an inner jaw portion 201 formed and dimensionedto cooperate with the outer jaw portion 200 (i.e., the elongatedablating surface 65) of clamping member 202 for clamping engagement ofthe interatrial septum wall 193 therebetween (FIG. 17). Hence, the innerjaw portion and the outer jaw portion move relative to one anotherbetween a clamped condition (FIG. 17 and in phantom lines in FIG. 28)and an unclamped condition (FIG. 14A and in solid lines in FIG. 28). Inthe unclamped condition, the inner jaw portion 201 of the attachmentdevice 203 is positioned away from the outer jaw portion 200 to permitinitial insertion of the distal end 165 of the outer jaw portion 200 ofthe clamping probe 198 into the fourth penetration 160, as will bediscussed.

The attachment device 203 is preferably provided by a generallystraight, elongated attachment shaft 206 having a first elbow portion207 positioned between the attachment shaft 206 and a generally straightinner jaw portion 201. FIG. 28 best illustrates that the first elbowportion of inner jaw portion 201 has an arc length and radius ofcurvature substantially similar to that of the outer jaw portion 200.Further, the length of the inner jaw portion is preferably about 2.0 mmto about 6.0 mm.

In the preferred form, the attachment shaft 206 is slidably coupled tothe clamping shaft 66 through a slidable coupling device 208 enablingsliding movement of the inner jaw portion 201 between the clamped andunclamped conditions. Preferably, a plurality of coupling devices 208are provided spaced-apart along the attachment shaft 206. Each couplingdevice includes a groove 210 (FIG. 29) formed for a sliding, snap-fitreceipt of the clamping shaft 66 therein for sliding movement of theattachment device in a direction along the longitudinal axis thereof.

The coupling devices are preferably composed of TEFLON®, plastic,polyurethane or the like, which is sufficiently resilient and bendableto enable the snap-fit engagement. Further, such materials includesufficient lubricating properties to provide slidable bearing support asthe clamping shaft 66 is slidably received in groove 210 to move innerjaw portion 201 between the clamped and unclamped conditions. Moreover,the coupling device configuration may permit rotational motion of theinner jaw portion 201 about the attachment shaft longitudinal axis, whenmoved in the unclamped condition. This ability further aids manipulationof the clamping probe 198 when introduced through the access device 68and insertion through the corresponding fourth penetration 160.

In the clamped condition, the inner jaw portion 201 is moved intoalignment with the outer jaw portion 200 of the clamping member 202 forcooperative clamping of the septum wall 193 therebetween. An alignmentdevice 211 is preferably provided which is coupled between the clampingmember 202 and the slidable attachment device 203 to ensure properalignment relative one another while in the clamped condition. This isparticularly necessary since the inner jaw portion 201 is capable ofrotational movement about the clamping shaft longitudinal axis, whenmoved in the unclamped condition. In the preferred embodiment, FIG. 30best illustrates that alignment device 211 is provided by a set ofspaced-apart rail members 212, 212' each extending from the outer jawportion 200 to the clamping shaft 66 of the clamping member 202. Therail members 212, 212' cooperate to define a slot 213 therebetween whichis dimensioned for sliding receipt of an elbow portion 207 of the innerjaw portion 201.

To further facilitate alignment between the inner jaw portion and theouter jaw portion, the elbow portion 207 of the inner jaw portion 201may include a rectangular cross-section dimensioned for squared receiptin the slot 213 formed between the rail members 212, 212'.Alternatively, alignment may be provided by the inclusion of a lockingdevice positioned at the handle of the probe, or by indexing detentsincluded on the clamping shaft.

Due to the relatively close spacing and placement of the third andfourth purse-string sutures 61, 62 in relation to the heart and theretractor 68, substantial precision is required for simultaneousinsertion of the jaw portion distal ends 165, 215. This problem isfurther magnified by the limited scope of visualization provided byeither direct viewing through the retractor and/or with the endoscope.Accordingly, the septum clamping probe 198 includes staggered length jawportions which position the distal end 165 of the outer jaw portion 200slightly beyond the distal end 215 of the inner jaw portion 201 tofacilitate alignment and insertion through the penetrations 158, 160. Inthe preferred form, the right angled clamping member 202 is initiallyintroduced through access device 68 for positioning of the distal endproximate the fourth purse-string suture 62. Upon alignment of the outerjaw distal end 165 with the fourth penetration 160, the clamping member202 is manipulated in the direction of arrow 197 for insertion of theouter jaw portion partially into the left atrium chamber. The initialinsertion depth of the tip is to be by an amount sufficient to retainthe outer jaw portion 200 in the fourth penetration, while permittingthe shorter length inner jaw portion 201 of the attachment device tomove from the unclamped condition toward the clamped condition (FIGS.18A and 18B).

It will be understood that the slidable attachment device 203, at thismoment, will either be unattached to the right angle probe or will beprepositioned in the unclamped condition. In the former event, theslidable attachment device 203 will be introduced through the accessdevice 68 and slidably coupled or snap fit to the clamping shaft 66 ofthe clamping member 202 via coupling devices 208. As the inner jawportion 201 is advanced in the direction of arrow 216 toward the clampedcondition, the attachment shaft 206 is rotated about its longitudinalaxis, if necessary, until the elbow portion 207 is aligned for receiptin the slot 213 formed between the spaced-apart rails members 212, 212'.In this arrangement, the inner jaw portion 201 will be aligned co-planarwith the outer jaw portion 200 of the clamping member 202.

The length of the inner jaw portion 201 is preferably shorter than thelength of the outer jaw portion 200 of clamping member 202 (preferablyby about 5 mm). With the distal end 165 of the outer jaw portion 200partially penetrating the fourth penetration 160 and the distal end 215of the inner jaw portion 201 aligned with the third penetration 158(FIG. 18B), the jaw portions are moved in the direction of arrow 197 toposition the jaws through the penetrations, on opposite sides of theseptum wall 193, and into the atrial chambers.

As shown in FIG. 17, the jaw portions 200, 201 are inserted to a desireddepth whereby the clamping probe can be aligned to pass through theanterior limbus of the fossa ovalis. When properly oriented, the jawportions can be moved fully to the clamped position exerting an inwardlydirected force (arrows 216, 216') toward opposed sides of theinteratrial septum wall 193. Subsequently, the cryogen is released intothe boiler chamber of the outer jaw portion of the clamping memberthereby cooling the ablating surface 65 and subjecting the septal wallto cryothermia.

Due in part to the substantial thickness of this heart tissue, to secureproper transmural ablation of the interior septal wall of the rightatrium, continuous contact of the ablating surface 65 therewith shouldtranspire for at least 3-4 minutes to create the anterior limbus of thefossa ovalis ablation. The clamping probe 198 and the septum wall are tobe properly defrosted and subsequently withdrawn from the third andfourth penetrations 158, 160, whereby the third and fourth purse-stringsutures 61, 62 are cinched tighter to prevent blood loss therefrom.

The length of the outer jaw portion is preferably between about 3 cm toabout 5 cm, while the length of the inner jaw portion is generally about5 mm less than the length of the outer jaw portion. Further, thediameter of the inner and outer jaw portions is preferably between about2-4 mm. The determination of the diameter and/or length of theparticular jaw portions and combinations thereof to be utilized willdepend upon the particular applications and heart dimensions.

The clamping arrangement of this probe enables a substantial clampingforce urged between the two opposed jaw portions for more efficient heatconduction. This configuration more effectively ablates the relativelythicker septum wall since greater leverage can be attained. Accordingly,in the preferred embodiment, only the outer jaw portion 200 (i.e., theablating surface 65) of the clamping member 202 needs to be cooled to beeffective. It will be appreciated, however, that the attachment device203 may include the boiler chamber to cool the inner jaw portion as wellfor ablation of both sides of the septum wall 193.

In an alternative embodiment of the clamping probe 198, as shown in FIG.31, the outer and inner jaw portions 200, 201 may cooperate to provide agap 217 at and between the outer elbow portion 166 and the inner elbowportion 207. This gap 217 is formed to accommodate the typically thickertissue juncture 218 where the septum wall 193 intersects the outeratrial wall 220. Hence, when the clamping probe 198 is moved to theclamped condition, the gap 217 is formed to receive this tissue juncture218 so that a more constant compression force may be applied across theseptum wall between the opposing jaws. This may be especiallyproblematic when the tissue juncture is significantly thicker than theseptum wall which, due to the disparity in thickness, may not enable thedistal ends of the respective jaw portions to effectively contact theseptum wall for transmural ablation thereof.

While FIG. 31 illustrates that the gap 217 is primarily formed throughthe offset curvature at the elbow portion 207 of inner jaw portion 201,it will be understood that the outer jaw portion 200 alone or acombination thereof may be employed to form the gap 217. Further, insome instances, the clamping probe 198 may be derived from the rightangle probe set forth above.

After completion of the above-mentioned series of elongated lesionsformed through the retractor, the right atrial appendage RAA may beexcised along the direction of solid line 221 in FIG. 3 and broken line222 in FIG. 19, to be described below. This excision is optionaldepending upon the particular circumstance since the risk of a fatalclot or thromboembolism is not as great as compared to left atrialappendage LAA. Should this excision be performed, the right atrialappendage RAA will preferably, first be sutured closed along broken line222 using conventional thoracoscopic instruments. This closure must behemostatic to prevent blood loss when the right atrial appendage isexcised. Once a hemostatic seal is attained, the appendage is excisedusing thoracoscopic scissors or an incision device.

While suturing is the preferred technique for hemostatically sealing theright atrial chamber, the right atrial appendage may first be surgicallyclosed along broken line 222 using staples. In this procedure, athoracoscopic stapling device would be inserted into the thoracic cavitythrough the retractor passageway 67 for access to the appendage.Moreover, the right atrial appendage may be conductively isolated byapplying a specially designed cryoprobe clamping device (not shown)formed to be placed across the base of the appendage to engage theexterior surface thereof. This lesion will extend completely around thebase along the line 221, 222 in FIGS. 3 and 19 which corresponds to theright atrial appendage excision in the prior surgical procedures.

The next series of lesions are accessed through the left atrium LA.Accordingly, a second access device 223, preferably the retractor 68,placed between the ribs on the left side of the patient P, usually inthe third or fourth intercostal space, and most preferably the thirdintercostal space as shown in FIG. 11A. Again, this percutaneouspenetration is positioned so that thoracoscopic instruments introducedthrough it may be directed toward the left atrium LA of the heart H.When additional maneuvering space is necessary, the intercostal spacebetween the ribs may be through spreading of the adjacent ribs, orportions of the ribs can be easily removed to widen the percutaneouspenetration. Further, the right lung will be re-inflated for use, whilethe left lung will be deflated to promote access while surgery is beingperformed. Other lung ventilation techniques may be employed such ashigh frequency ventilation without departing from the true spirit andnature of the present invention.

Subsequently, a pericardiotomy is performed to gain access to the leftside of the heart H utilizing thoracoscopic instruments introducedthrough the retractor 68. Using the same technique mentioned above, afifth 4-0 purse-string suture 63 is then formed in the atrial epicardiumof left atrial appendage LAA proximate a lateral midpoint thereof.Through a fifth penetration 161 formed central to the fifth purse-stringsuture 63, the orifices of the pulmonary veins can be accessed toprocure conductive isolation from the remainder of the left atrium LA.

In the preferred embodiment, the pulmonary vein isolation lesion 52 isformed using a two or more step process to completely encircle andelectrically isolate the four pulmonary veins. In the preferred form, afour-step technique is employed initially commencing with the use of aC-shaped, probe 225. As best viewed in FIGS. 19A and 32, the probeincludes an elongated shaft 66 and a C-shaped ablating end 70 mounted tothe distal end of the shaft 66. The C-shaped ablating end 70 is shapedand dimensioned such that a distal end of the ablating end curves aroundand terminates in a region proximate the longitudinal axis extendingthrough the shaft. The ablating end preferably includes an arc length ofabout 120° to about 180°, and a radius of the arc between about 6.0 mmto about 25.0 mm. This equates to an ablating surface length ofpreferably about 3.0 cm to about 6.0 cm.

With the aid of a thoracoscopic grasping instrument (not shown in FIG.19A), the distal end of probe 225 is inserted through fifth penetration161 to a position past the semi-circular ablating surface 65. A fifthtensioning sleeve 226 may be cinched tighter in the event to preventblood loss therefrom.

To create the first segment 227 of the pulmonary vein isolation lesion52, the distal end of the all-purpose probe is preferably positioned tocontact the pulmonary endocardial surface 228 of the left atrium LAabout 3-10 mm superior to the right superior pulmonary vein orifice 230.Through the manipulation of the probe handle from outside the body, abight portion 232 of the ablating surface 65 is positioned about 3-10 mmoutside of and partially encircling the right superior and left superiorpulmonary vein orifices 230, 231. Once aligned, the ablating surface 65of the probe is urged into ablative contact with the desired pulmonaryendocardial surface 228 to form about 1/3 of the pulmonary veinisolation lesion 52 (i.e., the first segment 227).

Without removing the probe 225 from the fifth penetration 161, the probe225 is rotated approximately 180° about the longitudinal axis of theprobe shaft 66 to reorient the ablating surface 65 to form the secondsegment 233 of the pulmonary vein isolation lesion 52. FIG. 19B bestillustrates that the bight portion 232 of the probe is positioned on theother side of pulmonary trunk to contact the pulmonary endocardium about3-10 mm just outside of and partially encircling the right inferior andleft inferior pulmonary vein orifices 235, 236. To ensure segmentcontinuity, the distal end of the probe is positioned to overlap thedistal of the first segment 227 by at least about 5 mm. Once the probebight portion 232 is aligned to extend around the pulmonary veinorifices, the ablating surface 65 thereof is urged into ablative contactwith the desired pulmonary endocardium to form the second segment 233 ofthe pulmonary vein isolation lesion 52. After ablative contact andsubsequent probe defrosting, the probe is retracted rearwardly from thefifth penetration 161 and removed from the second retractor 68. Anarticulating probe (not shown) may also be employed for this procedurewhich includes an ablating end capable of selected articulation of theablating surface to vary the curvature thereof. In this probe, thearticulation of the end may be manually or automatically controlledthrough control devices located at the handle portion of the probe. Thisprobe may be particularly suitable for use in the formation of thepulmonary vein isolation lesion due to the anatomical accessdifficulties.

Immediately following removal of the probe 225, a right angle probe isto be inserted through the fifth penetration 161 of the left atrialappendage LAA, in the manner above discussed, to create a third segment237 of the pulmonary vein isolation lesion 52. The formation of thissegment may require a different right angle probe, having a shorterlength ablating surface 65 (about 2.0 cm to about 6.0 cm) than that ofthe first right angle probe 163 utilized in the previous ablativeprocedures. As shown in FIGS. 19C, the ablating surface 65 is orientedjust outside the left superior pulmonary vein orifice 231 by at leastabout 5 mm. Again, to ensure proper segment continuity, it is importantto overlap the distal end of the ablating surface 65 with thecorresponding end of the lesion during the formation of the thirdsegment 237 of the pulmonary vein isolation lesion 52. After the probeis manually urged into contact with the desired pulmonary endocardialsurface 228, cryothermia is induced for the designated period totransmurally ablate the third segment 237 of the pulmonary veinisolation lesion 52. Subsequently, the right angle probe ablatingsurface 65 is properly defrosted to reverse cryoadhesion and enableseparation from the tissue.

Similar to the use of the probe 225, without removing the right angleprobe from the fifth penetration 161, the probe is rotated approximately180° about the longitudinal axis of the probe shaft to position theablating surface 65 just outside the left inferior pulmonary veinorifice 236 by at least about 5 mm (FIG. 19D). Again, to ensure propersegment continuity, it is important to overlap both the distal end andthe elbow portion of the ablating surface 65 with the corresponding endsof the second and third segments 233, 237 during the formation of thefourth segment 238 of the pulmonary vein isolation lesion 52. Fiberopticvisualization or the like is employed to facilitate proper continuitybetween the segments and placement of the probe. Once the probe is urgedinto contact with the desired left atrium interior surface, cryothermiais induced for the designated period to ablate the fourth segment of thepulmonary vein isolation lesion 52. After the right angle probe ablatingsurface 65 is properly defrosted, the probe is retracted rearwardly fromthe fifth penetration 161 and removed from the second retractor 68.

Formation of this last segment (i.e., fourth segment 238) completes thereentrant path isolation encircling the pulmonary veins (i.e., thepulmonary vein isolation cryolesion 52). It will be appreciated, ofcourse, that the order of the segment formation which collectivelydefines the pulmonary vein isolation lesion 52 may vary. It isimperative, however, that there be continuity between the four segments.If the four-step procedure is performed properly, the opposed ends ofthe four segments should all overlap and interconnect to form oneunitary ablation transmurally encircling the pulmonary trunk 108.

In accordance with the system and procedure of the present invention, analternative two-step endocardial procedure may be performed to isolatethe pulmonary veins. As shown in FIGS. 20A and 33, an S-shaped end probe240 is provided having a uniquely shaped, opened-looped ablating surface65 formed to substantially extend around or encircle the pulmonary veinorifices. The S-shaped probe 240 includes an elongated shaft 66 having asubstantially straight first portion 175 and a C-shaped second portion176 mounted to the distal end of the first portion and terminating at aposition proximate the longitudinal axis of the first portion 175 ofshaft 66. Mounted to the distal end of the C-shaped second portion 176is a C-shaped ablating end 70 which curves back in the oppositedirection such that the two C-shaped sections cooperate to form anS-shaped end. This unique shape enables the ablating surface 65 ofablating end 70 to have an arc length of between about 290° to about310°, with a radius of curvature of about 1.2 cm to about 3.0 cm.

FIG. 33 illustrates that the C-shaped ablating end 70 is shaped anddimensioned such that a distal end of the ablating end curves around andterminates in a region proximate the longitudinal axis extending throughthe shaft. Consequently, the ablating end 70, having a radius of about12.0 mm to about 25.0 mm, can then extend substantially around theendocardial surface of the pulmonary vein trunk. This is accomplished byproviding the C-shaped second portion 176 having a radius of curvatureof at least bout 5 mm to about 7 mm which enables the unimpeded flow ofcryogen through the delivery tube of the shaft 66. The elimination orsubstantial reduction of this C-shaped second portion 176 positionedjust before the C-shaped ablating end 70 would create such an acuteangle that the flow of cryogen about that angle may be impeded.

Using thoracoscopic grasping instruments, the distal end of this probeis carefully inserted through the fifth purse-string suture penetration161. Due in part to the unique near-circular shape of the ablatingsurface 65, initial insertion through the fifth penetration may be oneof the most difficult and problematic portions of this procedure.

As shown in FIG. 20A, after the ablating surface 65 of the probe 240 issuccessfully inserted through the fifth penetration 161, the loopedablating surface 65 is aligned and positioned to substantially encirclethe pulmonary vein orifices. Through manipulation of the probe handlefrom outside the thoracic cavity, the probe ablating surface 65 is urgedinto contact with the pulmonary endocardial surface 228 about 3-10 mmjust outside of the pulmonary vein orifices. Upon proper alignment andablative contact with the epicardial tissue, a first segment 241 of thistechnique is formed (FIG. 20B) which preferably constitutes at leastabout 3/4 of the pulmonary vein isolation lesion. After properdefrosting, the loop probe is removed from the fifth penetration andwithdrawn through the retractor.

To complete this alternative two-step procedure, an alternative rightangle probe, above-mentioned, is inserted through the fifth penetration161 upon removal of the S-shaped probe 240. FIG. 20B illustrates thatboth the distal end and the elbow portion of the probe ablating surface65 are aligned to overlap the corresponding ends of the first segment241 during the formation of a second segment 242 of the pulmonary veinisolation lesion 52. This ensures continuity between the two connectingsegments.

It will be understood that other shape probes may be employed to isolatethe pulmonary trunk. The particular customized shape may depend upon theindividual anatomical differences of the patient, especially sinceatrial fibrillation patients often have enlarged or distorted atria.

It may be beneficial to access and perform portions of either thefour-step procedure or the two-step procedure through the right side ofthe thoracic cavity. In these instances, access may be achieved throughthe first access device 68 and the fourth penetration 160 of the fourthpurse-string suture 62. Moreover, due to the arduous nature of theformation, placement and alignment between these segments composing theendocardial pulmonary vein isolation lesion in either the two or foursegment procedure, it may be necessary to ablate an epicardial lesion243 in the epicardial surface 168 encircling the pulmonary veins 108 toensure effective transmural tissue ablation for pulmonary veinisolation. Referring to FIGS. 21 and 33, an epicardial pulmonary veinloop probe 240, substantially similar to the probe employed in theprocedure of FIG. 20A, is provided for introduction through thepassageway of the retractor. This probe instrument includes anopen-looped ablating surface 65 defining an opening 245 (FIG. 33) formedfor passage of the pulmonary veins 108 therethrough. Using thoracoscopicgrasping instruments, the probe 240 is situated under the pulmonaryveins wherein the pulmonary veins 108 are urged through the opening 245in the looped ablating surface. Once the ablating surface 65 is alignedto contact a pulmonary epicardial surface 168 of the pulmonary veins 108at a position opposite the epicardial pulmonary vein isolation lesion52, cryogenic liquid is introduced into the boiler chamber of the loopprobe 240 for cryogenic cooling of the ablating surface 65. Aftercontact for the designated period (2-4 minutes) and proper probedefrosting, the loop probe is separated from the pulmonary trunk andretracted rearwardly out of the retractor 68.

Alternatively, this pulmonary epicardial surface isolation may beperformed from the right side of the thoracic cavity through the firstaccess device 68 (not shown). In this alternative method, theopen-looped ablating surface 65 of the loop probe 240 is positionedbehind the superior vena cava 111, across the anterior surface of theright pulmonary veins, and underneath the inferior vena cava 103. Onceproperly positioned, the epicardial surface 168 of the pulmonary trunk108 can be ablated.

Turning now to FIG. 22, formation of the left atrial anteromedial lesion246 will be described in detail. This lesion 246 is relatively shortextending only about 5-7 mm from the anteromedial portion of the leftatrial appendage LAA to the pulmonary vein isolation lesion 52 proximatea central portion between the left superior and inferior pulmonary veinorifices 231 236. Due to the position of this lesion and the flexiblenature of the appendage tissue, any one of a number of probes alreadymentioned, such as the probes illustrated in FIG. 32, the right angleprobe (FIG. 24) or the pulmonary vein to mitral valve probe (FIG. 34),can be employed for this task. Typically, the probe device 247 of FIG.34 is employed which includes an elongated shaft 66 having a first elbowportion 166 positioned between a relatively straight first portion 175and a generally straight second portion 176. The first elbow portion hasan arc length of about 45° to about 65° and a radius of curvature ofabout 3.2 cm to about 5.7 cm. Further, a second elbow portion 177 ispositioned between the second portion 176 and the ablating end 70,angling the ablating end back toward the longitudinal axis of the firstportion 175 of the elongated shaft 66. The ablating end 70 preferablyincludes the second elbow portion 177, having an arc length of about 80°to about 100°, and a radius of curvature of about 6.0 mm to about 1.9mm. This translates to an ablating surface of about 2.0 cm to about 6.0cm in length.

One of the above-mentioned probes will be introduced through the secondretractor 68 where the distal end of the probe will be inserted throughthe same fifth penetration 161 central to the fifth purse-string suture63. Once the selected probe 247, as shown in FIG. 22, is properlyaligned, the ablating surface 65 is urged into contact with the atrialendocardial surface of the left atrial appendage LAA for localizedablation. Subsequently, the left atrial anteromedial lesion 246 will beformed.

Since the left atrial wall at the anteromedial portion thereof isexceedingly thin, this transmural ablation could be performed fromoutside the heart H. Hence, upon contact of the ablating surface of aselected probe (not shown) with the atrial epicardial surface of theleft atrial appendage LAA, localized, transmural cryothermia may beapplied externally/epicardially to form this left atrial anteromediallesion 246.

The last lesion to be performed through the fifth penetration 161 is theposterior vertical left atrial lesion 248, also known as the coronarysinus lesion (FIG. 23), extending from the pulmonary vein isolationlesion 52 to the annulus 250 of the mitral valve MV. This lesion may becritical since improper ablation may enable atrial conduction tocontinue in either direction beneath the pulmonary veins. This mayresult in a long macro-reentrant circuit that propagates around theposterior-inferior left atrium, the atrial septum, the anterior-superiorleft atrium, the lateral wall of the left atrium beneath the excisedleft atrial appendage, and back to the posterior inferior left atrium.

Therefore, it is imperative that the coronary sinus be ablatedcircumferentially and transmurally in the exact plane of the atriotomyor lesion. Proper transmural and circumferential ablation near thecoronary sinus effectively eliminates the need for dividing all atrialmyocardial fibers traversing the fat pad of the underlyingatrioventricular groove.

In the preferred embodiment, a modified probe 251 (FIG. 35) is employedto ablate this critical coronary sinus lesion 248. This probe 251includes an elongated shaft 66 having a first elbow portion 166positioned between a generally straight first portion 175 and agenerally straight second portion 176. The first elbow portion has anarc length of about 30° to about 50° and a radius of curvature of about1.2 cm to about 3.0 cm. Mounted at the distal end of the second portion176 is the ablating end which is substantially similar in shape to theablating end of the probe of FIG. 32. The ablating end 70 curves backtoward the longitudinal axis of the first portion 175 of the elongatedshaft 66.

Again, this interior region of the heart H is accessed through the fifthpenetration 161, via the second access device 223. The distal end of theprobe 251, is positioned through the penetration in the same manner asprevious ablations. The unique curvature of this probe 251 enablesmanipulation of the ablating surface 65 from outside the thoracic cavityinto proper alignment. FIG. 23 best illustrates that ablating surface 65is moved into contact with the endocardial surface of the left atrialwall atrium for localized ablation extending from the pulmonary veinisolation lesion 52 to the mitral valve annulus 250. Particular care, asmentioned above, is taken to assure that this lesion extends through thecoronary sinus for circumferential electrical isolation thereof. Aftercontact for the designated period of 2-4 minutes, the ablating surface65 of the probe is properly defrosting and the probe 251 is retractedrearwardly from the fifth penetration 161 for removal from theretractor. Subsequently, the fifth penetration 161 is further cinched toprevent blood lose through the fifth purse-string suture 63.

Due to the criticality of the circumferential ablation of the coronarysinus during formation of the pulmonary vein to mitral valve annuluslesion 248, an epicardial ablation may be performed on a portion of theoutside heart wall opposite the endocardial ablation of the coronarysinus. Thus, the placement of this additional lesion (not shown) must bein the same plane as the coronary sinus lesion 248 (i.e., to the mitralvalve annulus lesion) to assure circumferential ablation of the coronarysinus. This is performed by introducing a standard probe through theretractor 68, and strategically contacting the epicardial surface at thedesired location opposite the coronary sinus lesion.

Upon completion of the above-mentioned series of elongated lesions, theleft atrial appendage LAA is excised along the direction of broken line252 in FIG. 23, similar to that of the prior procedures. This excisionis considered more imperative than the excision of the right atrialappendage RAA since the threat of thromboembolism or clotting would morelikely be fatal, induce strokes or cause other permanent damage. In thepreferred form, this excision is performed in the same manner as theexcision of the right atrial appendage (i.e., through suturing orstapling. After hemostatic closure is attained, the left atrialappendage LAA is excised using thoracoscopic scissors or an incisiondevice. This left appendagectomy will extend completely around the baseof the left atrial appendage along the solid line 252 in FIG. 3 or thebroken line 253 in FIG. 23, which corresponds to the left atrialappendage excision in prior procedures.

Alternatively, the probes may be formed and dimensioned for contact withthe epicardial surface 168 of the heart H. In these instances, nopurse-string suture may be necessary for elongated transmural ablation.As an example, as best viewed in FIG. 36, a right-angle clamp type probe255 is provided having an outer clamping portion 256 coupled to andformed to cooperate with a right angle probe or inner clamping portion257 for transmural ablation of the heart wall through contact withepicardial surface 168 of the heart H. In this embodiment, an outer jawportion 258 of outer clamping portion 256 is relatively thin (about 0.5mm to about 2.0 mm in diameter) and preferably needle shaped tofacilitate piercing of the heart wall at puncture 260. At the end of theneedle-shaped outer clamping portion 256 is a pointed end 261 whichenables piercing of the heart wall without requiring an initial incisionand subsequent purse-string suture to prevent blood loss through thepuncture 260.

Similar to clamping probe 198, when properly positioned, the outer andinner jaw portions 258, 262 of inner clamping portion 257 are movedinwardly in the direction of arrows 216, 216' (the outer jaw portion 258contacting endocardial surface 228, and the inner jaw portion 262contacting epicardial surface 168) to clamp the heart wall therebetween.FIG. 36 illustrates that inner jaw portion 262 includes ablation end 70having ablation surface 65 which contacts epicardial surface 168 forablation. Upon withdrawal of the needle-shaped outer jaw portion 258from the heart wall, the puncture 260 may be closed through a singlesuture (not shown).

In these embodiments, an alignment device 263 is provided whichcooperates between the outer and inner clamping portions 256, 257 foroperating alignment between the outer jaw portion 258 and the inner jawportion 262. This alignment device may be provided by any conventionalalignment mechanism such as those alignment devices employed in theclamping probe 198.

To ensure transmural ablation, the needle-shaped outer jaw portion 258may incorporate a temperature sensor 265 (FIG. 36) embedded in orpositioned on the outer jaw portion to measure the temperature of theendocardial surface. Measurement of the proper surface temperature willbetter ensure transmural ablation. These temperature sensors may beprovided by a variety of conventional temperature sensors.

Referring to FIGS. 37-40, another probe 280 is shown. A cryogen deliverytube 282 is positioned within an outer tube 284. A tip 286 seals an endof the outer tube 284. The delivery tube 282 is coupled to the source ofcryogen (not shown) for delivering the cryogen to a boiler chamber 288.The cryogen is exhausted from the boiler chamber 288 through the annulararea between the delivery tube 282 and outer tube 284. The delivery tube282 has an end cap 290 which receives first and second tubes 292, 294for delivery of cryogen to the boiler chamber 288 from the delivery tube282. The first tube 292 has an exhaust port 296 which extends furtherinto the boiler chamber 288 than an exhaust port 298 of the second tube294 so that the cryogen is distributed throughout the boiler chamber288. Although FIG. 38 depicts only the first and second outlet tubes292, 294, any number of tubes may be provided.

Ablating surface 300 of the outer tube 284 is preferably made of ahighly thermally conductive material such as copper. Referring to theend view of FIG. 40, the ablating surface 300 preferably has a ribbedinner surface 302 for enhanced thermal conduction between the boilerchamber 288 and the ablating surface 300. The probe 280 may take any ofthe configurations described herein.

Referring to FIGS. 41 and 42, another probe 306 is shown which has adevice for adjusting the delivery rate of cryogen. The delivery tube 308includes an inner tube 310 and an outer tube 312. The inner and outertubes 310, 312 have holes 314, 316 therein through which the cryogen isdelivered to boiler chamber 318. The outer tube 312 is slidable relativeto the inner tube 3 10 and can be locked relative to the inner tube 310at a number of discrete positions where the holes 314 in the inner tube310 are aligned with the holes 316 in the outer tube 312. The holes 314in the inner tube 310 are larger than holes 316 in the outer tube 312 sothat when the outer tube 312 is in the position of FIG. 41 a largeramount of cyrogen is delivered than when the outer tube 312 is in theposition of FIG. 42. Thus, the amount of cyrogen delivered, andtherefore the rate of ablation and temperature of the probe 306, can bechanged by moving the outer tube 312 relative to the inner tube 310. Thedelivery tube 308 may be used in the manner described above with any ofthe probe configurations described herein.

Referring to FIGS. 43 and 44, still another probe 318 is shown whichincludes suction ports 320 for ensuring intimate contact between theablating surface 322 and the tissue. The suction ports 320 are coupledto a longitudinal channel 324 which is coupled to a vacuum source forapplying suction. A cryogen delivery tube 326 delivers cryogen to boilerchamber 328 in the manner described herein.

Referring to FIGS. 45-47, a probe 330 having a malleable shaft 332 isshown. A malleable metal rod 334 is coextruded with a polymer 336 toform the shaft 332. A tip 338 having a boiler chamber 340 is attached tothe shaft 332. The rod 334 permits the user to shape the shaft 332 asnecessary so that the tip 338 can reach the tissue to be ablated. Thetip 338 has fittings 342 which are received in a cryogen exhaust path344 and a cryogen delivery path 346 in the shaft 332. The rod 334 ispreferably made of stainless steel and the polymer 336 is preferablypolyurethane. The tip 338 may be made of a suitable thermally conductivematerial such as copper. Cryogen is delivered through ports 348 in adelivery tube 350 and is expanded in the boiler chamber 340. The cryogenis then withdrawn through the exhaust path 344.

Finally, as set forth in the parent application incorporated herein byreference, access devices may be placed in the heart walls to enable thepassage of the probes through the wells of the access devices.

While the present invention has been primarily directed toward ablationfrom the endocardial surfaces of the atria, it will be understood thatmany lesions or portions of the lesions may be created through ablationof the endocardial surfaces of the atria employing the present probes.While the specific embodiments of the invention described herein willrefer to a closed-chest surgical procedure and system for the treatmentof medically refractory atrial fibrillation, it is understood that theinvention will be useful in ablation of other tissue structures,including surgical treatment of Wolfe-Parkinson-White (WPW) Syndrome,ventricular fibrillation, congestive heart failure and other proceduresin which interventional devices are introduced into the interior of theheart, coronary arteries, or great vessels. The present inventionfacilitates the performance of such procedures through percutaneouspenetrations within intercostal spaces, eliminating the need for amedian sternotomy or other form of gross thoracotomy. However, as willbe apparent although not preferred, the system and procedure of thepresent invention could be performed in an open-chest surgical procedureas well.

What is claimed is:
 1. A method of ablating epicardial tissue around thepulmonary veins, comprising the steps of:providing at least one ablationdevice having at least one ablating element; introducing the ablationdevice into the patient's chest; positioning the ablating element incontact with a location on an epicardial surface of the heart; andablating tissue to form a lesion around the pulmonary veins with the atleast one ablating element positioned at the location on the epicardialsurface to form at least part of the lesion around the pulmonary veins.2. The method of claim 1, wherein:the ablating step is carried out toablate tissue around the pulmonary veins to treat anelectrophysiological disease.
 3. The method of claim 1, wherein:theproviding step is carried out with the ablating device having at leastone vacuum port coupled to a source of suction; and the ablating step iscarried out with the at least one vacuum port being adhered to astructure to stabilize the device during the ablating step.
 4. Themethod of claim 3, wherein:the ablating step is carried out with the atleast one suction port being adhered to the surface of the patient'sheart.
 5. The method of claim 1, wherein:the providing step is carriedout with the ablating device having a curved portion for extendingaround at least one of the pulmonary veins.
 6. The method of claim 1,wherein:the providing step is carried out with the ablating elementablating tissue using RF, ultrasound, microwave, laser, heat, chemicalagents, biological agents and light activated agents.
 7. The method ofclaim 1, wherein:the introducing step is carried out without cutting thepatient's ribs.
 8. The method of claim 1, wherein:the ablating step iscarried out by forming transmural lesions in the tissue around thepulmonary veins.
 9. The method of claim 1, wherein:the ablating step iscarried out by encircling the pulmonary veins.
 10. The method of claim9, wherein:the providing step is carried out with the ablating deviceforming a loop which encircles the pulmonary veins.
 11. The method ofclaim 10, wherein:the providing step is carried out with the loop havingan opening therein.